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 | 1 |
| 2 | 4 |
| 3 | 24 |
| 4 | 336 |
| 5 | 5520 |
| 6 | 203040 |
| 7 | 7025760 |
| 8 | 510370560 |
| 9 | 30163311360 |
| 10 | 3577017024000 |
| 11 | 319851801561600 |
| 12 | 55850407258060800 |
| 13 | 7021439018770176000 |
| 14 | 1692163531361176473600 |
| 15 | 284409062346887622144000 |
| 16 | 90395009213694143422464000 |
| 17 | 19571060809440210728706048000 |
| 18 | 7929132907666579072319471616000 |