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 | 60 |
| 6 | 180 |
| 7 | 630 |
| 8 | 2520 |
| 9 | 7560 |
| 10 | 25200 |
| 11 | 92400 |
| 12 | 369600 |
| 13 | 1201200 |
| 14 | 4204200 |
| 15 | 15765750 |
| 16 | 63063000 |
| 17 | 214414200 |
| 18 | 771891120 |
| 19 | 2933186256 |
| 20 | 11732745024 |
| 21 | 41064607584 |
| 22 | 150570227808 |
| 23 | 577185873264 |
| 24 | 2308743493056 |
| 25 | 8245512475200 |