A081380 - cp's OEIS frontend

A081380 Numbers k such that the sets of prime factors (ignoring multiplicity) of A000203(k) = sigma(k) and of A001157(k) = sigma_2(k) are identical.

n	a(n)
1	1
2	180
3	1444
4	12996
5	23805
6	36100
7	52020
8	60228
9	64980
10	68832
11	95220
12	301140
13	324900
14	344160
15	481824
16	1505700
17	1718721
18	1720800
19	2275758
20	2409120
21	3755844
22	6874884
23	6879645
24	7965153
25	8593605
26	11378790
27	12045600
28	15930306
29	17405892

[1, 180, 1444, 12996, 23805, 36100, 52020, 60228, 64980, 68832, 95220, 301140, 324900, 344160, 481824, 1505700, 1718721, 1720800, 2275758, 2409120, 3755844, 6874884, 6879645, 7965153, 8593605, 11378790, 12045600, 15930306, 17405892]

cp's OEIS Frontend

A081380 Numbers k such that the sets of prime factors (ignoring multiplicity) of A000203(k) = sigma(k) and of A001157(k) = sigma_2(k) are identical.

Table of values

List of values