OFFSET
1,2
COMMENTS
Fermat's little theorem shows that this sequence contains no primes. Related to Giuga's conjecture that the sum is -1 iff n is prime. - Charles R Greathouse IV, Jun 10 2011
Is this is the disjoint union of all multiples of 4 and {1} and A121707 (n^3 divides Sum_{k<n} k^n)? - M. F. Hasler, Jul 22 2019
LINKS
Ivan Neretin, Table of n, a(n) for n = 1..10000
MATHEMATICA
is191677[n_]:=Mod[Sum[PowerMod[k, n - 1, n], {k, 1, n - 1}], n] == 0;
Select[Range[300], is191677]
PROG
(PARI) select( is_A191677(n)=!sum(k=1, n-1, Mod(k, n)^(n-1)), [1..200]) \\ M. F. Hasler, Jul 22 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
José María Grau Ribas, Jun 10 2011
STATUS
approved