A056550 - cp's OEIS frontend

A056550 Numbers k such that Sum_{j=1..k} sigma(j) is divisible by k, where sigma(j) = sum of divisors of j (A000203).

n	a(n)
1	1
2	2
3	8
4	11
5	17
6	63
7	180
8	259
9	818
10	2161
11	4441
12	8305
13	11998
14	694218
15	3447076
16	4393603
17	57402883
18	73459800
19	121475393
20	2068420025
21	5577330586
22	13320495021
23	35297649260
24	138630178659
25	988671518737
26	1424539472772
27	3028785109162
28	13702718147734
29	21320824383487

[1, 2, 8, 11, 17, 63, 180, 259, 818, 2161, 4441, 8305, 11998, 694218, 3447076, 4393603, 57402883, 73459800, 121475393, 2068420025, 5577330586, 13320495021, 35297649260, 138630178659, 988671518737, 1424539472772, 3028785109162, 13702718147734, 21320824383487]

cp's OEIS Frontend

A056550 Numbers k such that Sum_{j=1..k} sigma(j) is divisible by k, where sigma(j) = sum of divisors of j (A000203).

Table of values

List of values