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 | 2 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 6 |
| 6 | 20 |
| 7 | 180 |
| 8 | 180 |
| 9 | 20 |
| 10 | 70 |
| 11 | 1120 |
| 12 | 2520 |
| 13 | 1120 |
| 14 | 70 |
| 15 | 252 |
| 16 | 6300 |
| 17 | 25200 |
| 18 | 25200 |
| 19 | 6300 |
| 20 | 252 |
| 21 | 924 |
| 22 | 33264 |
| 23 | 207900 |
| 24 | 369600 |
| 25 | 207900 |
| 26 | 33264 |
| 27 | 924 |
| 28 | 3432 |
| 29 | 168168 |
| 30 | 1513512 |
| 31 | 4204200 |
| 32 | 4204200 |
| 33 | 1513512 |
| 34 | 168168 |
| 35 | 3432 |
| 36 | 12870 |
| 37 | 823680 |
| 38 | 10090080 |
| 39 | 40360320 |