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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.

A291881 Numbers n such that sigma(sigma(n)) = sigma(sigma(n)-n) + sigma(n); that is, f(g(n)) = g(f(n)) where f = A000203 and g = A001065.

Table of values

n a(n)
1 2
2 38040
3 51888
4 236644
5 260880
6 3097024
7 5283852
8 5667312
9 11777472
10 46120848
11 52981252
12 69128640
13 121352208
14 330364848
15 485906400
16 662736600
17 769422720
18 1111869360
19 1267978320
20 1272335760
21 1426817904
22 1807128528
23 2107406448
24 2381691312
25 2452404544
26 2691587568

List of values

[2, 38040, 51888, 236644, 260880, 3097024, 5283852, 5667312, 11777472, 46120848, 52981252, 69128640, 121352208, 330364848, 485906400, 662736600, 769422720, 1111869360, 1267978320, 1272335760, 1426817904, 1807128528, 2107406448, 2381691312, 2452404544, 2691587568]

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

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