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.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 31 |
| 5 | 236 |
| 6 | 2166 |
| 7 | 22722 |
| 8 | 269889 |
| 9 | 3567412 |
| 10 | 51765431 |
| 11 | 816476196 |
| 12 | 13892821878 |
| 13 | 253442895075 |
| 14 | 4930644856063 |
| 15 | 101830536332051 |
| 16 | 2223767436058566 |
| 17 | 51172807259226084 |
| 18 | 1237092039069090235 |
| 19 | 31332521053777095784 |
| 20 | 829389782837272248191 |
| 21 | 22894754438382163120136 |