A000441 - cp's OEIS frontend

A000441 a(n) = Sum_{k=1..n-1} ksigma(k)sigma(n-k).

n	a(n)
1	0
2	1
3	9
4	34
5	95
6	210
7	406
8	740
9	1161
10	1920
11	2695
12	4116
13	5369
14	7868
15	9690
16	13640
17	16116
18	22419
19	25365
20	34160
21	38640
22	50622
23	55154
24	73320
25	77225
26	100100
27	107730
28	135576
29	141085
30	182340
31	184760
32	233616
33	243408
34	297738
35	301420
36	385110
37	377511
38	467210
39	478842

[0, 1, 9, 34, 95, 210, 406, 740, 1161, 1920, 2695, 4116, 5369, 7868, 9690, 13640, 16116, 22419, 25365, 34160, 38640, 50622, 55154, 73320, 77225, 100100, 107730, 135576, 141085, 182340, 184760, 233616, 243408, 297738, 301420, 385110, 377511, 467210, 478842]

cp's OEIS Frontend

A000441 a(n) = Sum_{k=1..n-1} ksigma(k)sigma(n-k).

Table of values

List of values

cp's OEIS Frontend

A000441 a(n) = Sum_{k=1..n-1} k*sigma(k)*sigma(n-k).

Table of values

List of values

A000441 a(n) = Sum_{k=1..n-1} ksigma(k)sigma(n-k).