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 | 2 |
| 3 | 12 |
| 4 | 432 |
| 5 | 64240 |
| 6 | 33904800 |
| 7 | 61721081184 |
| 8 | 394586260943616 |
| 9 | 9146766152111641344 |
| 10 | 792073976107698469670400 |
| 11 | 261895415169919230764987845120 |
| 12 | 335402460348866803020064114666616832 |
| 13 | 1678893205649791601327398844631544110815232 |