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 | 2 |
| 4 | 9 |
| 5 | 24 |
| 6 | 160 |
| 7 | 1350 |
| 8 | 10353 |
| 9 | 89936 |
| 10 | 910656 |
| 11 | 10070730 |
| 12 | 120546745 |
| 13 | 1566125352 |
| 14 | 21934589664 |
| 15 | 329037515534 |
| 16 | 5264316535905 |
| 17 | 89493067364640 |
| 18 | 1610885172539008 |
| 19 | 30606819613112466 |
| 20 | 612136012448309481 |
| 21 | 12854856587833586360 |
| 22 | 282806860558105285920 |