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 | 3 |
| 3 | 12 |
| 4 | 36 |
| 5 | 216 |
| 6 | 1020 |
| 7 | 8160 |
| 8 | 61920 |
| 9 | 507744 |
| 10 | 4383392 |
| 11 | 52600704 |
| 12 | 624249600 |
| 13 | 8739494400 |
| 14 | 109190390400 |
| 15 | 1583122968000 |
| 16 | 25318378008000 |
| 17 | 455730804144000 |
| 18 | 8193040840252800 |
| 19 | 163860816805056000 |
| 20 | 3256371347261760000 |
| 21 | 67204676251838361600 |
| 22 | 1366492477414792734720 |