This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A098375 #15 Apr 26 2025 03:27:44
%S A098375 1,1,21,2801,1964956409,5897061106093,345112805910366790769,
%T A098375 5724003102153474225966281,5621496960287976955328551429580241,
%U A098375 2417009997194019381479073094599560492013039757981,331241570655571671768537062318886722305299290781512129
%N A098375 (1/p)*abs(p*(p^(p-1)-1)*B(p-1)-1) when p runs through the primes and B(k) denotes the k-th Bernoulli's number.
%C A098375 Conjecture: p is an odd prime iff p divides p*(p^(p-1)-1)*B(p-1)-1. Seems to be the equivalent (with integer moduli) to Agoh's conjecture (which involves rational moduli).
%H A098375 Amiram Eldar, <a href="/A098375/b098375.txt">Table of n, a(n) for n = 1..58</a>
%H A098375 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/AgohsConjecture.html">Agoh's Conjecture</a>.
%t A098375 f[p_] := Abs[p * (p^(p-1)-1) * BernoulliB[p-1] - 1]; Table[f[p]/p, {p, Prime[Range[10]]}] (* _Amiram Eldar_, Apr 26 2025 *)
%o A098375 (PARI) a(n)=(1/prime(n))*(prime(n)*(prime(n)^(prime(n)-1)-1)*bernfrac(prime(n)-1)-1);
%Y A098375 Cf. A027641, A027642, A089655.
%K A098375 nonn
%O A098375 1,3
%A A098375 _Benoit Cloitre_, Oct 26 2004