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%I #5 Mar 30 2012 18:39:23
%S 1,1,21,2801,1964956409,5897061106093,345112805910366790769,
%T 5724003102153474225966281,5621496960287976955328551429580241,
%U 2417009997194019381479073094599560492013039757981
%N (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 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 E. Weisstein, <a href="http://mathworld.wolfram.com/AgohsConjecture.html">Agoh's conjecture</a>.
%o (PARI) a(n)=(1/prime(n))*(prime(n)*(prime(n)^(prime(n)-1)-1)*bernfrac(prime(n)-1)-1)
%Y Cf. A089655.
%K nonn
%O 1,3
%A _Benoit Cloitre_, Oct 26 2004
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