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 | 4 |
| 4 | 33 |
| 5 | 136 |
| 6 | 1825 |
| 7 | 10956 |
| 8 | 163009 |
| 9 | 1575568 |
| 10 | 23894721 |
| 11 | 280090900 |
| 12 | 5410068961 |
| 13 | 73066199064 |
| 14 | 1483125027553 |
| 15 | 25872759745756 |
| 16 | 561027082980225 |
| 17 | 10796395534986016 |
| 18 | 266457543316023169 |
| 19 | 5743345672152317988 |
| 20 | 152031229968147150241 |
| 21 | 3717043193920429157800 |
| 22 | 104377807879737865769121 |