OFFSET
1,1
COMMENTS
Conjecture: (1 + Sum_{k(even)=2..p-1} 2*k^(p-1))/p is an integer iff p is an odd prime.
MATHEMATICA
a[n_] := Module[{p = Prime[n + 1]}, (1 + 2 * Sum[k^(p - 1), {k, 2, p - 1, 2}])/p]; Array[a, 11] (* Amiram Eldar, Oct 29 2020 *)
PROG
(PARI) a(n) = my(p=prime(n+1)); (1 + sum(k=1, (p-1)\2, 2*(2*k)^(p-1)))/p; \\ Michel Marcus, Oct 29 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Davide Rotondo, Oct 29 2020
STATUS
approved