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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 35214 |
| 9 | 229378 |
| 10 | 1408522 |
| 11 | 8370900 |
| 12 | 49154431 |
| 13 | 288653307 |
| 14 | 1703668022 |
| 15 | 10115769088 |
| 16 | 60332300930 |
| 17 | 360602808068 |
| 18 | 2156022737216 |
| 19 | 12883491408374 |
| 20 | 76929443106701 |
| 21 | 459100718065735 |
| 22 | 2739019173150040 |
| 23 | 16339850317888878 |
| 24 | 97481064340012333 |