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 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 116 |
| 6 | 702 |
| 7 | 4944 |
| 8 | 39722 |
| 9 | 358578 |
| 10 | 3593664 |
| 11 | 39595440 |
| 12 | 475746474 |
| 13 | 6190838544 |
| 14 | 86740334160 |
| 15 | 1301939398080 |
| 16 | 20842001737224 |
| 17 | 354469125185880 |
| 18 | 6382790173842480 |
| 19 | 121310821042966800 |
| 20 | 2426863248540057480 |
| 21 | 50975836645480342560 |
| 22 | 1121691979824460425360 |