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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 5 |
| 4 | 22 |
| 5 | 258 |
| 6 | 1628 |
| 7 | 18052 |
| 8 | 145976 |
| 9 | 1837272 |
| 10 | 18407664 |
| 11 | 265312848 |
| 12 | 3184567136 |
| 13 | 52020223648 |
| 14 | 728304073664 |
| 15 | 13317701313600 |
| 16 | 213083801827200 |
| 17 | 4314950946864000 |
| 18 | 77669134543011584 |
| 19 | 1725980887361498368 |
| 20 | 34519618313219995136 |
| 21 | 835374767116711506432 |
| 22 | 18378244896208168541184 |