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 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 2 |
| 6 | 12 |
| 7 | 73 |
| 8 | 519 |
| 9 | 4193 |
| 10 | 38084 |
| 11 | 384010 |
| 12 | 4256112 |
| 13 | 51428023 |
| 14 | 672849973 |
| 15 | 9475970455 |
| 16 | 142929221024 |
| 17 | 2298778304796 |
| 18 | 39270796040273 |
| 19 | 710146895061598 |
| 20 | 13551969914092152 |
| 21 | 272168729108017393 |
| 22 | 5738224038694033364 |