A291164 Numbers k such that 2^psi(k) == -1 (mod k) where psi(k) = A001615(k).

1, 5, 25, 125, 625, 3125, 4097, 7361, 15625, 69649, 78125, 85073, 125137, 390625, 658529, 987377, 1184033, 1953125, 2127329, 2358529, 3187313, 3999137, 9765625, 11194993, 16777217, 16785409, 20128561, 20502593, 30030769, 36164593, 40094993, 48828125, 50281793

Offset: 1

Author

Altug Alkan, Aug 19 2017

Keywords

• nonn

Examples

			7361 is a term because 7361 = 17*433 divides 2^psi(7361) + 1 = 2^(18*434) + 1.
		

Crossrefs

Cf. A001615, A276238.

Programs

PARI

a001615(n) = n*sumdivmult(n, d, issquarefree(d)/d);
is(n) = Mod(2,n)^a001615(n)==-1;