0,2

Table of n, a(n) for n=0..77.

Juri-Stepan Gerasimov,x = A001511(A051027(A000079(x))),SeqFan list, Aug 19 2019.

a(n) = A001511(A051027(A000079(n))).

a(0) = A001511(A051027(A000079(0))) = A001511(A051027(A000079(2^0))) = A001511(A051027(1)) = A001511(1) = 1.

(MAGMA) [Valuation(2*SumOfDivisors(SumOfDivisors(2^n)), 2): n in [0..89]];

(PARI) a(n) = valuation(2*sigma(sigma(2^n)), 2); \\ Michel Marcus, Aug 06 2019

Cf. A000043 (numbers m such that m - 1 divides a(m - 1) - 2), A000079, A001511, A051027, A090748.

Sequence in context: A279678 A222283 A182487 * A061117 A255171 A323712

Adjacent sequences: A309527 A309528 A309529 * A309531 A309532 A309533

nonn

Juri-Stepan Gerasimov, Aug 06 2019

approved