English

A search for primes $p$ such that Euler number $E_{p-3}$ is divisible by $p$

Number Theory 2018-04-10 v1

Abstract

Let p>3p>3 be a prime. Euler numbers Ep3E_{p-3} first appeared in H. S. Vandiver's work (1940) in connection with the first case of Fermat Last Theorem. Vandiver proved that xp+yp=zpx^p+y^p=z^p has no solution for integers x,y,zx,y,z with gcd(xyz,p)=1\gcd(xyz,p)=1 if Ep30(modp)E_{p-3}\equiv 0 (\bmod p). Numerous combinatorial congruences recently obtained by Z.-W. Sun and by Z.-H. Sun involve the Euler numbers Ep3E_{p-3}. This gives a new significance to the primes pp for which Ep30(modp)E_{p-3}\equiv 0 (\bmod p). For the computation of residues of Euler numbers Ep3E_{p-3} modulo a prime pp, we use the congruence which runs significantly faster than other known congruences involving Ep3E_{p-3}. Applying this congruence, a computation via {\tt Mathematica 8} shows that only three primes less than 10710^7 satisfy the condition Ep30(modp)E_{p-3}\equiv 0 (\bmod p) (such primes are 149, 241 and 2946901, and they are given as a Sloane's sequence A198245). By using related computational results and statistical considerations similar to those on search for Wieferich and Fibonacci-Wieferich and Wolstenholme primes, we conjecture that there are infinitely many primes pp such that Ep30(modp)E_{p-3}\equiv 0 (\bmod p). Moreover, we propose a conjecture on the asymptotic estimate of number of primes pp in an interval [x,y][x,y] such that Ep3A(modp)E_{p-3}\equiv A (\bmod p) for some integer AA with A[K,L]|A|\in [K,L].

Keywords

Cite

@article{arxiv.1212.3602,
  title  = {A search for primes $p$ such that Euler number $E_{p-3}$ is divisible by $p$},
  author = {Romeo Mestrovic},
  journal= {arXiv preprint arXiv:1212.3602},
  year   = {2018}
}

Comments

10 pages. We reported that only three primes $p\in\{149,241,2946901\}$ less than $10^7$ satisfy the condition that related Euler numbers $E_{p-3}$ are divisible by $p$. Nevertheless, we conjecture that there are infinitely many such primes

R2 v1 2026-06-21T22:54:47.756Z