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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A291880 Numbers n such that phi(n) - 1 | sigma(n).

Table of values

n a(n)
1 3
2 4
3 5
4 6
5 8
6 10
7 20
8 22
9 40
10 76
11 80
12 108
13 160
14 204
15 320
16 640
17 1072
18 1280
19 2560
20 4192
21 5120
22 10240
23 20480
24 40960
25 49344
26 81920
27 163840
28 327680
29 655360
30 1310720
31 2621440
32 4197376
33 5242880
34 10485760
35 20971520
36 41943040
37 83886080
38 167772160
39 268460032
40 335544320
41 671088640
42 1073790976
43 1342177280
44 2684354560
45 5368709120

List of values

[3, 4, 5, 6, 8, 10, 20, 22, 40, 76, 80, 108, 160, 204, 320, 640, 1072, 1280, 2560, 4192, 5120, 10240, 20480, 40960, 49344, 81920, 163840, 327680, 655360, 1310720, 2621440, 4197376, 5242880, 10485760, 20971520, 41943040, 83886080, 167772160, 268460032, 335544320, 671088640, 1073790976, 1342177280, 2684354560, 5368709120]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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