A283118 a(n) = sigma(5*n).

6, 18, 24, 42, 31, 72, 48, 90, 78, 93, 72, 168, 84, 144, 124, 186, 108, 234, 120, 217, 192, 216, 144, 360, 156, 252, 240, 336, 180, 372, 192, 378, 288, 324, 248, 546, 228, 360, 336, 465, 252, 576, 264, 504, 403, 432, 288, 744, 342, 468, 432, 588, 324, 720

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), this sequence (k=5), A224613 (k=6), A283078 (k=7), A283122 (k=8), A283123 (k=9).

Cf. A008587.

Programs

Mathematica

Table[DivisorSigma[1, 5 n], {n, 56}] (* Michael De Vlieger, Mar 01 2017 *)

PARI

a(n) = sigma(5*n) \\ Amiram Eldar, Dec 16 2022

Formula

a(n) = A000203(5*n).

Sum_{k=1..n} a(k) = (29*Pi^2/60) * n^2 + O(n*log(n)). - Amiram Eldar, Dec 16 2022