A171732 a(n) = Sum_{d|n} d*2^(d^2).

2, 34, 1538, 262178, 167772162, 412316861986, 3940649673949186, 147573952589676675106, 21760664753063325144712706, 12676506002282294014967199825954, 29243015907268149203883755326167580674, 267608942382367477698428619271780750388889122

Offset

1,1

Links

Table of n, a(n) for n=1..12.

Example

L.g.f.: L(x) = 2*x + 34*x^2/2 + 1538*x^3/3 + 262178*x^4/4 + ...
exp(L(x)) = 1 + 2*x + 19*x^2 + 548*x^3 + 66749*x^4 + ... (A158099).

Mathematica

a[n_] := DivisorSum[n, # * 2^(#^2) &]; Array[a, 10] (* Amiram Eldar, Aug 18 2023 *)

Prog

(PARI) a(n)=sumdiv(n, d, d*2^(d^2))

Crossrefs

Cf. A158099.

Sequence in context: A187546 A195005 A215957 * A291903 A340863 A198977

Adjacent sequences: A171729 A171730 A171731 * A171733 A171734 A171735

Keyword

nonn

Author

Paul D. Hanna, Dec 16 2009

Extensions

a(11)-a(12) from Amiram Eldar, Aug 18 2023

Status

approved