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 | 63 |
| 2 | 1260 |
| 3 | 13860 |
| 4 | 103950 |
| 5 | 594594 |
| 6 | 2774772 |
| 7 | 11042460 |
| 8 | 38648610 |
| 9 | 121671550 |
| 10 | 350414064 |
| 11 | 935402832 |
| 12 | 2338507080 |
| 13 | 5521090680 |
| 14 | 12394285200 |
| 15 | 26606398896 |
| 16 | 54875697723 |
| 17 | 109181751525 |
| 18 | 210275965900 |
| 19 | 393175282500 |
| 20 | 715579014150 |
| 21 | 1270517841450 |
| 22 | 2205030964500 |
| 23 | 3747302149500 |