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 | 0 |
| 2 | 12 |
| 3 | 540 |
| 4 | 21000 |
| 5 | 785820 |
| 6 | 28956312 |
| 7 | 1058809752 |
| 8 | 38545567632 |
| 9 | 1399354322652 |
| 10 | 50707958458872 |
| 11 | 1835099465988360 |
| 12 | 66348521294296176 |
| 13 | 2397139928161319640 |
| 14 | 86559958069097395440 |
| 15 | 3124302168622853150640 |
| 16 | 112729791393354644416800 |