A091986 a(0)=1, a(n) = sigma_3(2n).

1, 9, 73, 252, 585, 1134, 2044, 3096, 4681, 6813, 9198, 11988, 16380, 19782, 25112, 31752, 37449, 44226, 55261, 61740, 73710, 86688, 97236, 109512, 131068, 141759, 160454, 183960, 201240, 219510, 257544, 268128, 299593, 335664, 358722, 390096, 442845

Offset

0,2

Links

Table of n, a(n) for n=0..36.

Formula

Sum_{k=1..n} a(k) ~ (17*zeta(4)/8) * n^4. - Amiram Eldar, Dec 12 2023

Mathematica

Join[{1}, Table[DivisorSigma[3, n], {n, 2, 80, 2}]]  (* Harvey P. Dale, Feb 26 2011 *)

Prog

(PARI) a(n) = if(n < 1, 1, sigma(2*n, 3)); \\ Amiram Eldar, Dec 12 2023

Crossrefs

Bisection of A001158.

Cf. A013662, A045823.

Sequence in context: A043079 A367697 A099973 * A096129 A365304 A291700

Adjacent sequences: A091983 A091984 A091985 * A091987 A091988 A091989

Keyword

nonn,easy

Author

N. J. A. Sloane, Mar 20 2004

Status

approved