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.

A231484 Numbers n such that n, sigma(n) and sigma(sigma(n)) are odd.

Table of values

n a(n)
1 1
2 81
3 1476326929
4 10994571025
5 61436066769
6 98551417041
7 119582481249
8 141447449025
9 220545762129
10 388895668225
11 619568914129
12 890560253025
13 970952066161
14 2580138650961
15 3076652813521
16 3739640454225
17 4138876942929
18 4758545225281
19 9262289646801
20 26494089912081

List of values

[1, 81, 1476326929, 10994571025, 61436066769, 98551417041, 119582481249, 141447449025, 220545762129, 388895668225, 619568914129, 890560253025, 970952066161, 2580138650961, 3076652813521, 3739640454225, 4138876942929, 4758545225281, 9262289646801, 26494089912081]

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

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