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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 25 |
| 5 | 108 |
| 6 | 788 |
| 7 | 4740 |
| 8 | 44445 |
| 9 | 339632 |
| 10 | 3625136 |
| 11 | 35508536 |
| 12 | 462626736 |
| 13 | 5273725108 |
| 14 | 76634997096 |
| 15 | 1047347436984 |
| 16 | 17542238923677 |
| 17 | 268193251446228 |
| 18 | 4949536256552648 |
| 19 | 86303019303031400 |
| 20 | 1768833677916545596 |
| 21 | 34165810747993948664 |
| 22 | 759192269597947084836 |