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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 44 |
| 6 | 265 |
| 7 | 1854 |
| 8 | 14833 |
| 9 | 133496 |
| 10 | 1334961 |
| 11 | 14684570 |
| 12 | 145510740 |
| 13 | 1314803006 |
| 14 | 11013531389 |
| 15 | 87155940048 |
| 16 | 663875231097 |
| 17 | 4947896842392 |
| 18 | 36563337902968 |
| 19 | 270617834212996 |
| 20 | 2021217246729905 |
| 21 | 15317729587621252 |
| 22 | 118254506519672137 |
| 23 | 924131987256868248 |