A335913 a(n) = A225546(sigma(n)).

1, 4, 3, 256, 8, 12, 6, 64, 4294967296, 18, 12, 768, 512, 24, 24

Offset: 1

Author

Antti Karttunen, Jul 07 2020

Keywords

• nonn

Comments

Term a(16) has 309 digits (1025 bits).

This is not multiplicative. Even though a(2*3) = a(2)*a(3), a(2*7) = a(2)*a(7), and a(3*5) = a(3)*a(5), we still have a(2*5) = 18 <> a(2)*a(5) = 4*8 = 32.

Links

• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A048675, A225546, A331733, A331750, A331751.

Cf. also A326042.

Programs

Mathematica

Array[If[# == 1, 1, Times @@ Flatten@ Map[Function[{p, e}, Map[Prime[Log2@ # + 1]^(2^(PrimePi@ p - 1)) &, DeleteCases[NumberExpand[e, 2], 0]]] @@ # &, FactorInteger[#]]] &@ DivisorSigma[1, #] &, 15] (* Michael De Vlieger, Jul 08 2020 *)

PARI

A335913(n) = A225546(sigma(n));

Formula

a(n) = A225546(A000203(n)).

A048675(a(n)) = A331750(n).