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A309530 Number of power-of-two-divisors of sum of divisors of sum of divisors of powers of two: a(n) = A001511(A051027(A000079(n))). 1
1, 3, 4, 4, 6, 4, 8, 5, 5, 10, 5, 6, 14, 12, 12, 6, 18, 10, 20, 11, 9, 9, 6, 8, 8, 18, 6, 15, 7, 16, 32, 7, 11, 22, 17, 14, 7, 24, 22, 13, 5, 13, 11, 12, 20, 10, 7, 11, 9, 16, 33, 22, 6, 10, 15, 17, 28, 12, 6, 20, 62, 36, 12, 9, 24, 16, 5, 26, 12, 26, 10, 18, 6, 12, 16, 28, 19, 26 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

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

FORMULA

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

EXAMPLE

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

PROG

(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

CROSSREFS

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

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Aug 06 2019

STATUS

approved

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Last modified August 9 22:24 EDT 2020. Contains 336326 sequences. (Running on oeis4.)