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 | 8 |
| 1 | 21 |
| 2 | 80 |
| 3 | 390 |
| 4 | 2304 |
| 5 | 15960 |
| 6 | 126720 |
| 7 | 1134000 |
| 8 | 11289600 |
| 9 | 123742080 |
| 10 | 1480550400 |
| 11 | 19199980800 |
| 12 | 268240896000 |
| 13 | 4016428416000 |
| 14 | 64163222323200 |
| 15 | 1089292748544000 |
| 16 | 19583731335168000 |
| 17 | 371693362360320000 |
| 18 | 7426753498644480000 |
| 19 | 155827373623713792000 |