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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.

A117285 Numbers k for which the cototient k-phi(k) is a pentagonal number.

Table of values

n a(n)
1 1
2 2
3 3
4 5
5 7
6 11
7 13
8 17
9 18
10 19
11 20
12 22
13 23
14 25
15 29
16 30
17 31
18 37
19 41
20 43
21 47
22 53
23 59
24 61
25 67
26 71
27 73
28 75
29 79
30 83
31 89
32 97
33 101
34 102
35 103
36 107
37 109
38 110
39 113
40 127
41 131
42 132
43 137
44 139
45 140
46 149
47 151
48 155
49 157
50 163
51 167
52 173
53 179
54 181
55 191
56 193
57 197
58 199
59 203
60 211
61 223

List of values

[1, 2, 3, 5, 7, 11, 13, 17, 18, 19, 20, 22, 23, 25, 29, 30, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 75, 79, 83, 89, 97, 101, 102, 103, 107, 109, 110, 113, 127, 131, 132, 137, 139, 140, 149, 151, 155, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 203, 211, 223]

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

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