A343781 - cp's OEIS frontend

A343781 a(n) = Sum_{k=1..floor(n/2)} sigma_k(n-k), where sigma_k(n) is the sum of the k-th powers of the divisors of n.

n	a(n)
1	0
2	1
3	3
4	9
5	17
6	55
7	111
8	457
9	943
10	4962
11	11148
12	69526
13	159402
14	1161340
15	2765874
16	22829766
17	55192956
18	510771772
19	1257880780
20	12870681814
21	32042113008
22	359566186586
23	904795505226
24	11043196798176
25	28002785395660
26	369463867367567
27	943392140873807
28	13378621275148931

[0, 1, 3, 9, 17, 55, 111, 457, 943, 4962, 11148, 69526, 159402, 1161340, 2765874, 22829766, 55192956, 510771772, 1257880780, 12870681814, 32042113008, 359566186586, 904795505226, 11043196798176, 28002785395660, 369463867367567, 943392140873807, 13378621275148931]

cp's OEIS Frontend

A343781 a(n) = Sum_{k=1..floor(n/2)} sigma_k(n-k), where sigma_k(n) is the sum of the k-th powers of the divisors of n.

Table of values

List of values