A108639 - cp's OEIS frontend

A108639 a(n) = Sum_{k=1..n} sigma_{n-k}(k), where sigma_m(k) = Sum_{j|k} j^m.

n	a(n)
1	1
2	3
3	6
4	13
5	29
6	77
7	229
8	771
9	2863
10	11573
11	50365
12	234161
13	1156039
14	6031751
15	33130187
16	190929778
17	1151198268
18	7243777234
19	47462906927
20	323188163753
21	2282922216819
22	16701529748621
23	126359471558613
24	987316752551419

[1, 3, 6, 13, 29, 77, 229, 771, 2863, 11573, 50365, 234161, 1156039, 6031751, 33130187, 190929778, 1151198268, 7243777234, 47462906927, 323188163753, 2282922216819, 16701529748621, 126359471558613, 987316752551419]

cp's OEIS Frontend

A108639 a(n) = Sum_{k=1..n} sigma_{n-k}(k), where sigma_m(k) = Sum_{j|k} j^m.

Table of values

List of values