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.

A249903 Numbers n such that 2n+1 and sigma(n) are both noncomposite numbers.

Table of values

n a(n)
1 1
2 2
3 9
4 729

List of values

[1, 2, 9, 729]