A277859 Least k > 1 such that 1^(k-1) + 2^(k-1) + 3^(k-1) + … + (k-1)^(k-1) - n == 0 (mod k)

2, 3, 2, 4, 2, 7, 2, 3, 2, 11, 2, 4, 2, 3, 2, 4, 2, 19, 2, 3, 2, 23, 2, 4, 2, 3, 2, 4, 2, 31, 2, 3, 2, 5, 2, 4, 2, 3, 2, 4, 2, 9, 2, 3, 2, 47, 2, 4, 2, 3, 2, 4, 2, 5, 2, 3, 2, 59, 2, 4, 2, 3, 2, 4, 2, 45, 2, 3, 2, 15, 2, 4, 2, 3, 2, 4, 2, 9, 2, 3, 2, 83, 2, 4, 2

Offset

1,1

Comments

a(2*n-1) = 2.

a(n) = n + 1 for some prime n + 1 congruent to {2, 3} mod 4.

Links

Paolo P. Lava, Table of n, a(n) for n = 1..1000

Example

a(8) = 3 because:
1^(2-1) - 8 = -7 but -7 mod 2 = 1;
1^(3-1) + 2^(3-1) - 8 = -3 and  -3 mod 3 = 0;

Maple

P:=proc(q) local j, k, n; for n from 1 to q do for k from 2 to q do
if (add(j^(k-1), j=1..k-1)-n) mod k=0 then print(k); break; fi; od; od; end: P(10^3);

Crossrefs

Cf. A045326, A191677.

Sequence in context: A365784 A235912 A339749 * A308566 A288535 A105117

Adjacent sequences: A277856 A277857 A277858 * A277860 A277861 A277862

Keyword

nonn,easy

Author

Paolo P. Lava, Nov 02 2016

Status

approved