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.

A319170 Triangular numbers of the form 2..21..1; n_times 2 followed with n_times 1; n >= 1.

Table of values

n a(n)
1 21
2 2211
3 222111
4 22221111
5 2222211111
6 222222111111
7 22222221111111
8 2222222211111111
9 222222222111111111
10 22222222221111111111
11 2222222222211111111111
12 222222222222111111111111
13 22222222222221111111111111
14 2222222222222211111111111111
15 222222222222222111111111111111
16 22222222222222221111111111111111

List of values

[21, 2211, 222111, 22221111, 2222211111, 222222111111, 22222221111111, 2222222211111111, 222222222111111111, 22222222221111111111, 2222222222211111111111, 222222222222111111111111, 22222222222221111111111111, 2222222222222211111111111111, 222222222222222111111111111111, 22222222222222221111111111111111]