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 | 8 |
| 3 | 48 |
| 4 | 192 |
| 5 | 1920 |
| 6 | 23040 |
| 7 | 322560 |
| 8 | 1290240 |
| 9 | 7741440 |
| 10 | 154828800 |
| 11 | 3406233600 |
| 12 | 40874803200 |
| 13 | 1062744883200 |
| 14 | 29756856729600 |
| 15 | 892705701888000 |
| 16 | 3570822807552000 |
| 17 | 121407975456768000 |
| 18 | 1456895705481216000 |
| 19 | 55362036808286208000 |
| 20 | 1107240736165724160000 |