A331750 - OEIS

A331750

a(n) = A048675(sigma(n)).

0, 2, 2, 8, 3, 4, 3, 6, 32, 5, 4, 10, 9, 5, 5, 1024, 5, 34, 6, 11, 5, 6, 5, 8, 1024, 11, 7, 11, 7, 7, 5, 12, 6, 7, 6, 40, 129, 8, 11, 9, 11, 7, 18, 12, 35, 7, 6, 1026, 130, 1026, 7, 17, 7, 9, 7, 9, 8, 9, 8, 13, 1025, 7, 35, 1073741824, 12, 8, 66, 13, 7, 8, 7, 38, 2049, 131, 1026, 14, 7, 13, 8, 1027, 32, 13, 12, 13, 8, 20, 9

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OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

Index entries for sequences related to sigma(n)

FORMULA

a(n) = A048675(A000203(n)).

Additive with a(p^e) = A048675(sigma(p^e)) = A048675(1 + p + p^2 + ... + p^e).

MATHEMATICA

{0}~Join~Array[Total@ Map[#[[-1]]*2^(PrimePi[#[[1]]] - 1) &, FactorInteger@ DivisorSigma[1, #]] &, 86, 2] (* Michael De Vlieger, Feb 08 2020, after Jean-François Alcover at A048675 *)

PROG

(PARI)

A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; };

A331750(n) = A048675(sigma(n));

CROSSREFS

Cf. A000203, A048675, A324573, A331751.

Sequence in context: A283990 A021442 A296851 * A166853 A143440 A093731

Adjacent sequences: A331747 A331748 A331749 * A331751 A331752 A331753

KEYWORD

nonn

AUTHOR

Antti Karttunen, Feb 05 2020

STATUS

approved