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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.

A230770 Numbers n such that sigma(n) + phi(n) is a composite number of the form p^k where p is a prime.

Table of values

n a(n)
1 2
2 4
3 12
4 15
5 110
6 121
7 125
8 511
9 908
10 2047
11 31269
12 58252
13 180544
14 2275680
15 3776877
16 4164717
17 4835820
18 8386433
19 8388607
20 32284479
21 60333777
22 82628532
23 122016110
24 174438012
25 238609292
26 513528686
27 515718093
28 919749786
29 1043394771
30 3851465145
31 4264386607

List of values

[2, 4, 12, 15, 110, 121, 125, 511, 908, 2047, 31269, 58252, 180544, 2275680, 3776877, 4164717, 4835820, 8386433, 8388607, 32284479, 60333777, 82628532, 122016110, 174438012, 238609292, 513528686, 515718093, 919749786, 1043394771, 3851465145, 4264386607]

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

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