cp's OEIS Frontend

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.

A135241 Numbers k such that sigma(sigma(k)) = 2*phi(k).

Table of values

n a(n)
1 13
2 43
3 109
4 151
5 883
6 2143
7 116581
8 388537
9 1711663
10 2498227
11 4004107
12 5550331
13 12641137
14 13617361
15 18591967
16 20755393
17 22998397
18 26838523
19 29308291
20 34564351
21 36300841
22 44829073
23 82368469
24 149460841
25 184988197
26 238225003
27 252757891
28 340428853

List of values

[13, 43, 109, 151, 883, 2143, 116581, 388537, 1711663, 2498227, 4004107, 5550331, 12641137, 13617361, 18591967, 20755393, 22998397, 26838523, 29308291, 34564351, 36300841, 44829073, 82368469, 149460841, 184988197, 238225003, 252757891, 340428853]

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

Content is available under The OEIS End-User License Agreement.