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 | 3 |
| 2 | 60 |
| 3 | 756 |
| 4 | 7920 |
| 5 | 75075 |
| 6 | 668304 |
| 7 | 5697720 |
| 8 | 47070144 |
| 9 | 379632825 |
| 10 | 3004501500 |
| 11 | 23417943120 |
| 12 | 180241588800 |
| 13 | 1372689900036 |
| 14 | 10360604899680 |
| 15 | 77595170756400 |
| 16 | 577241321893632 |
| 17 | 4268838966063525 |
| 18 | 31404136939468020 |
| 19 | 229951212925133700 |
| 20 | 1676737802322198000 |
| 21 | 12180171012442098435 |