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 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 4 |
| 6 | 1 |
| 7 | 24 |
| 8 | 6 |
| 9 | 192 |
| 10 | 432 |
| 11 | 17280 |
| 12 | 10 |
| 13 | 207360 |
| 14 | 51840 |
| 15 | 322560 |
| 16 | 1360800 |
| 17 | 696729600 |
| 18 | 3225600 |
| 19 | 12541132800 |
| 20 | 39191040 |
| 21 | 27869184000 |
| 22 | 1316818944000 |
| 23 | 115880067072000 |
| 24 | 349272000 |
| 25 | 2781121609728000 |
| 26 | 17382010060800000 |