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.

A253849 Numbers k such that 2^sigma(k) - 1 is a prime.

Table of values

n a(n)
1 2
2 4
3 9
4 16
5 25
6 64

List of values

[2, 4, 9, 16, 25, 64]