A283078 a(n) = sigma(7*n).

8, 24, 32, 56, 48, 96, 57, 120, 104, 144, 96, 224, 112, 171, 192, 248, 144, 312, 160, 336, 228, 288, 192, 480, 248, 336, 320, 399, 240, 576, 256, 504, 384, 432, 342, 728, 304, 480, 448, 720, 336, 684, 352, 672, 624, 576, 384, 992, 400, 744, 576, 784, 432, 960

Offset: 1

Author

Seiichi Manyama, Feb 28 2017

Keywords

• nonn

Examples

			For n = 3, the divisors of 3*7 are {1, 3, 7, 21}. Now, 1 + 3 + 7 + 21 = 32. So, a(3) = 32. - _Indranil Ghosh_, Feb 28 2017
		

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), this sequence (k=7), A283122 (k=8), A283123 (k=9).

Cf. A008589.

Programs

Mathematica

Table[DivisorSigma[1,7n],{n,1,54}] (* Indranil Ghosh, Feb 28 2017 *)

PARI

a(n) = sigma(7*n) \\ Indranil Ghosh, Feb 28 2017

Formula

From Amiram Eldar, Dec 16 2022: (Start)

a(n) = A000203(7*n) = A000203(A008589(n)).

Sum_{k=1..n} a(k) = (55*Pi^2/84) * n^2 + O(n*log(n)). (End)