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.

A256439 Numbers k such that phi(k-1)+1 divides sigma(k).

Table of values

n a(n)
1 3
2 5
3 17
4 26
5 171
6 257
7 265
8 1921
9 9385
10 26665
11 65537
12 263041
13 437761
14 1057801
15 2038648321
16 10866583226
17 11453097097
18 982923711145

List of values

[3, 5, 17, 26, 171, 257, 265, 1921, 9385, 26665, 65537, 263041, 437761, 1057801, 2038648321, 10866583226, 11453097097, 982923711145]