\documentclass[11pt]{article} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{lmodern,amsmath,amssymb,amsthm,mathtools,booktabs,microtype} \usepackage[margin=1in]{geometry} \usepackage[colorlinks=true,linkcolor=blue,citecolor=blue,urlcolor=blue]{hyperref} \hypersetup{pdftitle={Irrational even beta values from powered hypergeometric kernels}, pdfauthor={twinheterodox}, pdfsubject={Working proof draft with exact computational certificates}} \usepackage{enumitem} \setlist{nosep} \newtheorem{theorem}{Theorem} \newtheorem{proposition}[theorem]{Proposition} \newtheorem{lemma}[theorem]{Lemma} \newtheorem{corollary}[theorem]{Corollary} \newcommand{\Z}{\mathbb Z}\newcommand{\Q}{\mathbb Q} \newcommand{\Fp}{\mathbb F_p}\newcommand{\vp}{v_p} \newcommand{\ind}{\mathbf 1} \title{Irrational even beta values from powered hypergeometric kernels} \author{twinheterodox\\[2pt]\normalsize Prepared with Codex} \date{11 November 2026} \begin{document} \maketitle \begin{abstract} For the Dirichlet beta function, we prove that at least one of $\beta(6),\beta(8),\ldots,\beta(74)$ is irrational, and that at least one of $\beta(8),\beta(10),\ldots,\beta(110)$ is irrational. These shorten the previously stated intervals with the same starting indices, whose upper endpoints are $92$ and $128$, respectively \cite[Section 8.2]{shifted}. The new bounds come from a different construction, based on powers of Krisman's hypergeometric kernel \cite{krisman}. \end{abstract} \section{Results and proof strategy}\label{sec:introduction} For $s>1$, the Dirichlet beta function is \[ \beta(s)=\sum_{t=0}^{\infty}\frac{(-1)^t}{(2t+1)^s}. \] Krisman \cite[Theorem 1.1]{krisman} proves that at least one of $\beta(4),\beta(6),\ldots,\beta(36)$ is irrational. We seek intervals that also omit $\beta(4)$, and in the second case below omit $\beta(6)$. \begin{theorem}\label{thm:main} Each of the following sets contains an irrational number: \[ \{\beta(6),\beta(8),\ldots,\beta(74)\},\qquad \{\beta(8),\beta(10),\ldots,\beta(110)\}. \] \end{theorem} Table~\ref{tab:comparison} compares these bounds with the earlier shifted-interval results \cite{shifted}. Each entry asserts the existence of one irrational value, with all indices even. The intervals overlap, so the two assertions of Theorem~\ref{thm:main} need not identify distinct irrational numbers. \begin{table}[ht] \centering \begin{tabular}{crrrr}\toprule & \multicolumn{2}{c}{\cite[Section 8.2]{shifted}} & \multicolumn{2}{c}{Theorem~\ref{thm:main}}\\ First index & Last index & Values & Last index & Values\\\midrule 6 & 92 & 44 & 74 & 35\\ 8 & 128 & 61 & 110 & 52\\\bottomrule \end{tabular} \caption{The earlier endpoints use parameters chosen for these particular starting indices. Each new interval removes nine candidate values.} \label{tab:comparison} \end{table} Sorokin \cite[Theorem S]{sorokin} proved that, for every sufficiently large odd $m$ and every even $h>100m\log m$, at least one of $\beta(m+1),\beta(m+3),\ldots,\beta(m+h-1)$ is irrational. The later result \cite[Theorem 1.2]{shifted} treats every even starting index and any prescribed number of irrational values. For one irrational value, \cite[Proposition B.1]{shifted} gives an upper endpoint below $18.58m$ for positive odd $m$, with first index $m+1$. We improve the two instances in the table. Corollary~\ref{cor:general} gives a criterion for further instances, with a finite nonvanishing condition that must still be checked. \subsection*{How the argument is organized} The irrationality contradiction has three requirements. For each target interval, we construct a sequence of rational linear forms in $1$ and the indicated beta values. After clearing the denominators of their coefficients, these forms must tend to zero and must be nonzero infinitely often. Under joint rationality, a single fixed denominator for the beta values would then give a sequence of integers tending to zero, with infinitely many nonzero terms. Krisman's construction already balances the cost of clearing denominators against the decay of a rational kernel. We retain that balance while changing the beta indices. Squaring the kernel gives zeros of order six, so four differentiations still leave zeros at the integers where they are needed. Reflection then makes $\beta(6)$ the first possible beta term. Cubing and differentiating six times similarly starts at $\beta(8)$. Section~\ref{sec:construction} explains this operation before writing its general form. The main arithmetic point in Section~\ref{sec:bounds} is that taking a power multiplies the initial valuation of a local series, while leaving its loss per Taylor coefficient unchanged. This permits the original denominator and decay estimates to scale together. Small forms could nevertheless be zero. To resolve that obstacle, Section~\ref{sec:dilation} follows the prime-dilation strategy of \cite[Section 6]{shifted}, which uses the auxiliary-prime principle of Lai and Sprang \cite[Lemma 2.3]{laisprang}. At indices equal to a fixed base index times a large prime, a rescaling makes all beta coefficients vanish modulo the prime, while the rational constant reduces to a fixed seed constant. Our adaptations account for Krisman's nonuniform pole orders and for the loss of the two outer zeros under dilation. The nonzero seed constants are checked in Section~\ref{sec:seed}. Thus the kernel and its estimates come from \cite[Sections 2--6]{krisman}; the nonvanishing strategy follows \cite[Section 6]{shifted}. The transfer under powers and the dilation calculation for this kernel are the additional arguments given here. The proof uses no irrationality result for Catalan's constant. \subsection*{Prerequisites and notation} The intended reader is familiar with partial fractions, formal Taylor series, arithmetic modulo primes, elementary prime valuations, and asymptotic estimates. Write $v_p$ for the valuation on $\Q$ normalized by $v_p(p)=1$, with $v_p(0)=+\infty$. The ring $\Z_{(p)}$ consists of rationals whose denominators are prime to $p$; an element of this ring is a unit when its numerator is also prime to $p$. Congruences between rationals are taken in this ring. These definitions suffice for all the local arguments below. The prime-number-theorem estimate we use is cited explicitly. \section{Raising the first beta index}\label{sec:construction} \subsection{The kernel we retain} We use Krisman's kernel because its denominator cost is already smaller than its real decay rate. Its integer zeros will remove initial summands and control rational correction terms; its half-integer poles produce beta values. The reflection symmetry will remove odd beta indices. Fix $r=7/6$ and $N=480$, and let $n$ tend to infinity through positive multiples of $N$. The choice $480=\operatorname{lcm}(160,6)$ makes all block endpoints and $rn$ integral, and makes $n$ even. The $28$ blocks, with total multiplicity $S=35$, have parameters \[ (\delta,m)=(0,8),\qquad (\kappa/160,1) \quad\left(\kappa\in\{1,\ldots,8\}\cup\{10,12,\ldots,46\}\right). \] The pole with address $j$ is at $t=-j-1/2$. A block $b$ adds multiplicity $m_b$ to each pole address in $I_b(n)=[\delta_b n,(1-\delta_b)n]\cap\Z$. Thus the total pole order at address $j$ is \[ B_j(n)=\sum_bm_b\ind_{j\in I_b(n)}. \] For example, at $n=480$ the outer block contributes eight copies of every address from $0$ to $480$; the blocks with $\kappa=1$ and $46$ contribute one copy on $[3,477]$ and $[138,342]$, respectively. The orders increase from $8$ near the ends to $35$ in the middle, and $B_{n-j}=B_j$. We often omit the argument $n$ from $B_j(n)$. Set $\Lambda_n=[-(1+r)n-1,rn]\cap\Z$. The kernel is \begin{equation}\label{eq:R} R_n(t)=\frac{(2t+n+1)\prod_{\ell\in\Lambda_n}(t-\ell)^3} {\prod_{j=0}^n(t+j+1/2)^{B_j}}. \end{equation} The linear factor $2t+n+1$ corrects the sign of reflection about $-(n+1)/2$, giving \begin{equation}\label{eq:reflection} R_n(-n-1-t)=R_n(t). \end{equation} At the central half-integer pole this factor cancels one order. We keep the nominal order $B_{n/2}=35$ in the formulas, allowing a zero leading coefficient. The excess of pole degree over zero degree grows at rate \[ G=\sum_bm_b(1-2\delta_b)-3(1+2r)=\frac{179}{10}. \] Indeed, \[ 3\#\Lambda_n=10n+6,\qquad \sum_{j=0}^nB_j=\frac{279}{10}n+35, \] so $\deg R_n=-Gn-28$. In particular the kernel is proper and decays rapidly at infinity. These are the parameters and identities of \cite[Section 2]{krisman}. \subsection{The square case, then the general form} Rivoal \cite[Section 2, Lemma 1]{rivoal} used differentiation to remove $\zeta(3)$ from linear forms in odd zeta values. Krisman \cite[Section 1.2]{krisman} adapted this device to even beta values. We use fourth derivatives instead of second derivatives to remove $\beta(4)$. For example, a partial-fraction term transforms as \[ \frac{c}{(t+j+1/2)^2} \quad\xrightarrow{\ d^4/dt^4\ }\quad \frac{120c}{(t+j+1/2)^6}. \] Alternating summation of the latter term produces $\beta(6)$ and a rational correction. A simple-pole term would instead produce $\beta(5)$, but reflection cancels that odd-index contribution. Fourth differentiation would destroy the triple zeros of $R_n$. Squaring first gives zeros of order six, so the differentiated function still vanishes at all the relevant integers. The cost is that the largest nominal pole order doubles from $35$ to $70$, allowing indices as large as $70+4=74$. Cubing gives zeros of order nine; six derivatives preserve them, and the largest possible index is $105+6=111$. Reflection cancels the $\beta(111)$ term, leaving $110$ as the largest possible index. This explains the endpoints in the theorem. For the shared proof, fix an integer $q\ge1$ independently of $n$ and put \begin{equation}\label{eq:L} L_{q,n}=\sum_{t=0}^{\infty}(-1)^t \frac{d^{2q}}{dt^{2q}}\bigl(R_n(t)^q\bigr). \end{equation} The zeros now have order $3q>2q$, and the degree bound gives absolute convergence. Write the partial fractions as \[ R_n(t)^q=\sum_{j=0}^n\sum_{i=1}^{qB_j} \frac{a_{q,n;j,i}}{(t+j+1/2)^i}. \] The rational correction at address $j$ is the omitted initial part of the beta series. More precisely, for $s>1$ define \[ \sigma_j(s)=\sum_{m=0}^{j-1}\frac{(-1)^m}{(2m+1)^s}, \qquad \sum_{t=0}^{\infty}\frac{(-1)^t}{(t+j+1/2)^s} =(-1)^j2^s\bigl(\beta(s)-\sigma_j(s)\bigr). \] The identity follows by replacing $t+j$ with a new summation index. With $(i)_d=i(i+1)\cdots(i+d-1)$, it gives \begin{equation}\label{eq:expansion} L_{q,n}=\sum_{j,i}(-1)^j2^{i+2q}(i)_{2q}a_{q,n;j,i} \bigl(\beta(i+2q)-\sigma_j(i+2q)\bigr). \end{equation} Reflection \eqref{eq:reflection} gives $a_{q,n;n-j,i}=(-1)^ia_{q,n;j,i}$. Since $n$ is even, pairing addresses $j$ and $n-j$ cancels the beta coefficient whenever $i$ is odd. Thus \begin{equation}\label{eq:target} L_{q,n}\in\Q+\sum_{j=q+1}^{\lfloor37q/2\rfloor}\Q\beta(2j). \end{equation} We have obtained exactly the required range of possible indices. It remains to show that clearing the rational coefficients is inexpensive enough to preserve decay, and then to prove nonvanishing. \section{Clearing denominators while preserving decay}\label{sec:bounds} \subsection{Why the arithmetic estimate survives a power} The relevant arithmetic is local at each pole. Remove the nominal pole at $t=-j-1/2$ and use a local variable $z$; the remaining Taylor series is \[ f_j(z)=(n-2j+2z)\prod_{\ell\in\Lambda_n}(-j-1/2-\ell+z)^3 \prod_{h\ne j}(h-j+z)^{-B_h}. \] For the $q$th power, the coefficient of pole order $i$ is therefore $a_{q,n;j,i}=[z^{qB_j-i}]f_j(z)^q$. Suppose a series $f(z)=\sum f_hz^h$ satisfies $v_p(f_h)\ge\nu-\lambda h$, where $\nu\in\Z$ and $\lambda\in\Z_{\ge0}$. Call this a $(\nu,\lambda)$ bound: $\nu$ is the initial valuation and $\lambda$ bounds the loss for each extra Taylor degree. The square case displays the useful feature: \[ [z^h]f(z)^2=\sum_{u+v=h}f_uf_v, \qquad v_p(f_uf_v)\ge2\nu-\lambda(u+v)=2\nu-\lambda h. \] The same convolution argument shows that $f^q$ has a $(q\nu,\lambda)$ bound. The initial valuation is multiplied by $q$, but the loss per degree is unchanged. Consequently \begin{equation}\label{eq:powerlocal} v_p(a_{q,n;j,i})\ge q\nu-\lambda(qB_j-i). \end{equation} If a harmonic correction of exponent $i+2q$ costs at most $(i+2q)\lambda$ powers of $p$, the combined bound is \begin{equation}\label{eq:costcancel} q\nu-\lambda(qB_j-i)-\lambda(i+2q) =q\bigl(\nu-\lambda(B_j+2)\bigr). \end{equation} This is exactly $q$ times the bound for the original second derivative. It explains both the choice of derivative order $2q$ and the use of the $q$th power of the original denominator multiplier. \subsection{The multiplier and its prime bounds} We now specify that multiplier so that every prime range can be checked. The notation below records the counts of numerator and denominator factors divisible by a prime, or their full valuations when prime powers must be counted. Put \[ M_n=19n/3+3,\quad Z=3\#\Lambda_n=10n+6,\quad \lambda_p=\lfloor\log_pM_n\rfloor\ (p\text{ odd}),\quad \lambda_2=\lfloor\log_2n\rfloor. \] All the nonzero integer differences in these local factors have absolute value below $M_n$. For an odd prime $p>n$, none of the pole differences is divisible by $p$. For odd $p\le n$, the condition $p^2>M_n$ means that each nonzero difference contains at most one factor of $p$, so divisibility counts suffice. Smaller primes can occur to higher powers and require full valuations. The prime $2$ needs separate treatment because the pole locations are half-integers. For $w_{j,\ell}=2j+1+2\ell$, define \begin{align*} \epsilon_p(j)&=3\#\{\ell\in\Lambda_n:p\mid w_{j,\ell}\} +\ind_{p\mid n-2j}-\sum_{h\ne j}B_h\ind_{p\mid h-j},\\ \nu_p(j)&=3\sum_{\ell\in\Lambda_n}v_p(w_{j,\ell}) -\sum_{h\ne j}B_hv_p(h-j)\quad(p\text{ odd}),\\ \nu_2(j)&=1-Z-\sum_{h\ne j}B_hv_2(h-j). \end{align*} The factor $3$ counts the triple zeros. At $2$, each half-integer numerator factor costs one power of $2$, explaining $-Z$, while the linear factor contributes the initial $+1$. Krisman's full-series estimate \cite[Lemma 4.3]{krisman}, with the choices in the proof of his Corollary 4.4, gives the following bounds for $f_j$: \begin{center} \begin{tabular}{ll}\toprule Prime range & $(\nu,\lambda)$ bound\\\midrule $p>n$, odd & $(0,0)$\\ $p\le n$, odd, $p^2>M_n$ & $(\epsilon_p(j),1)$\\ $p\le n$, odd, $p^2\le M_n$ & $(\nu_p(j),\lambda_p)$\\ $p=2$ & $(\nu_2(j),\lambda_2)$\\\bottomrule \end{tabular} \end{center} These are bounds on the whole local series, obtained by multiplying linear numerator factors and geometric denominator series. We can therefore apply \eqref{eq:powerlocal} to them. The original denominator multiplier is \begin{equation}\label{eq:E} E_p(n)=\begin{cases} \max_j(-\nu_2(j)+35\lambda_2),&p=2,\\ 0,&p>n\text{ odd},\\ \max_j(B_j+2-\epsilon_p(j)),&p\le n\text{ odd},\ p^2>M_n,\\ \max_j(-\nu_p(j)+37\lambda_p),&p\le n\text{ odd},\ p^2\le M_n, \end{cases} \qquad D_n=\prod_{p\le n}p^{E_p(n)}. \end{equation} Here $35$ is the maximum nominal pole order and $37=35+2$ includes the two derivatives in the original form. Some exponents $E_p$ may be negative, so $D_n$ is a positive rational multiplier rather than necessarily an integer. What matters is the integrality of the coefficients after multiplication. \begin{proposition}[Arithmetic transfer]\label{prop:arithmetic} Every rational coefficient of \eqref{eq:expansion}, after collecting equal beta values and the constant term, becomes an integer on multiplication by $D_n^q$. \end{proposition} \begin{proof} First take an odd prime $p\le n$. Each odd denominator in $\sigma_j(i+2q)$ has valuation at most the $\lambda$ in the relevant row of the table. Equations \eqref{eq:powerlocal}--\eqref{eq:costcancel} therefore bound the valuation of a constant summand below by $-qE_p(n)$. The same lower bound holds without the harmonic factor, hence for every beta coefficient. The factors $(i)_{2q}$ and $2^{i+2q}$ introduce no odd-prime denominators. At $2$ the harmonic denominators are odd. Keeping the factor $2^{i+2q}$, the valuation of a summand is at least \[ q\nu_2(j)-\lambda_2(qB_j-i)+i+2q \ge q\nu_2(j)-35q\lambda_2\ge-qE_2(n). \] It remains to treat odd primes $p>n$. All local coefficients are then $p$-integral. A harmonic denominator can still be divisible by $p$, so we use the integer zeros to replace a possibly bad partial sum by its complement. The use of zeros throughout the pole region to control the rational constant already appears in Zudilin \cite[proof of Lemma 1]{zudilin}. We follow Krisman's derivative version \cite[Lemma 4.6]{krisman}, with zero order $3q$ and derivative order $2q$. For $1\le\ell\le n$, put \[ T(\ell,j)=\sum_i(i)_{2q}a_{q,n;j,i}(j-\ell+1/2)^{-i-2q}. \] Reindexing the harmonic sums expresses the rational constant as $-\sum_{\ell=1}^n(-1)^\ell\sum_{j=\ell}^nT(\ell,j)$. Because $-\ell\in\Lambda_n$ and $3q>2q$, evaluation of the full partial-fraction sum gives \[ \sum_{j=0}^nT(\ell,j)=(R_n^q)^{(2q)}(-\ell)=0, \qquad \sum_{j=\ell}^nT(\ell,j)=-\sum_{j=0}^{\ell-1}T(\ell,j). \] The prime $p$ cannot divide denominators $2(j-\ell)+1$ on both sides: two such addresses would differ by a nonzero multiple of $p$ of absolute value at most $n
0$
and $\mathcal F(0)=0$, and set
\begin{align*}
\Phi(x)&=3\{\mathcal F(x+1+r)-\mathcal F(x-r)\}\\
&\hspace{1cm}-\sum_bm_b\{\mathcal F(x+1-\delta_b)-\mathcal F(x+\delta_b)\},
\qquad x\ge r,\\
A&=\frac{12507029707866288048422972493354331}
{790300921079786767495600904601600},\qquad V=-\frac{744}{25}.
\end{align*}
The bounds we use from \cite[Corollary 5.9 and Propositions 6.4--6.5]{krisman}
are
\begin{align}
\log D_n&\le G\log(n!)+n(A+20\log2+o(1)),\label{eq:Dsize}\\
0