A283237 a(n) = sigma_2(3*n).

10, 50, 91, 210, 260, 455, 500, 850, 820, 1300, 1220, 1911, 1700, 2500, 2366, 3410, 2900, 4100, 3620, 5460, 4550, 6100, 5300, 7735, 6510, 8500, 7381, 10500, 8420, 11830, 9620, 13650, 11102, 14500, 13000, 17220, 13700, 18100, 15470, 22100, 16820, 22750, 18500

Offset

1,1

Links

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Formula

a(n) = A001157(3*n).

Sum_{k=1..n} a(k) ~ (29*zeta(3)/9) * n^3. - Amiram Eldar, Dec 12 2023

Mathematica

Table[DivisorSigma[2, 3n], {n, 1, 43}] (* Indranil Ghosh, Mar 03 2017 *)

Prog

(PARI) a(n) = sigma(3*n, 2); \\ Indranil Ghosh, Mar 03 2017

Crossrefs

Sigma_2(k*n): A001157 (k=1), A099979 (k=2), this sequence (k=3).

Cf. A002117.

Sequence in context: A222633 A061861 A243226 * A036786 A085444 A102915

Adjacent sequences: A283234 A283235 A283236 * A283238 A283239 A283240

Keyword

nonn,easy

Author

Seiichi Manyama, Mar 03 2017

Status

approved