A283122 a(n) = sigma(8*n).

15, 31, 60, 63, 90, 124, 120, 127, 195, 186, 180, 252, 210, 248, 360, 255, 270, 403, 300, 378, 480, 372, 360, 508, 465, 434, 600, 504, 450, 744, 480, 511, 720, 558, 720, 819, 570, 620, 840, 762, 630, 992, 660, 756, 1170, 744, 720, 1020, 855, 961

Offset: 1

Author

Seiichi Manyama, Mar 01 2017

Keywords

• nonn

Links

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

Crossrefs

Sigma(k*n): A000203 (k=1), A062731 (k=2), A144613 (k=3), A193553 (k=4), A283118 (k=5), A224613 (k=6), A283078 (k=7), this sequence (k=8), A283123 (k=9).

Cf. A008590.

Programs

Mathematica

Table[DivisorSigma[1, 8 n], {n, 50}] (* Michael De Vlieger, Mar 01 2017 *)

PARI

a(n) = sigma(8*n) \\ Amiram Eldar, Dec 16 2022

Formula

a(n) = A000203(8*n).

Sum_{k=1..n} a(k) = (23*Pi^2/24) * n^2 + O(n*log(n)). - Amiram Eldar, Dec 16 2022