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 | 0 |
| 1 | 2 |
| 2 | 8 |
| 3 | 36 |
| 4 | 192 |
| 5 | 1200 |
| 6 | 8640 |
| 7 | 70560 |
| 8 | 645120 |
| 9 | 6531840 |
| 10 | 72576000 |
| 11 | 878169600 |
| 12 | 11496038400 |
| 13 | 161902540800 |
| 14 | 2440992153600 |
| 15 | 39230231040000 |
| 16 | 669529276416000 |
| 17 | 12093372555264000 |
| 18 | 230485453406208000 |
| 19 | 4622513815535616000 |
| 20 | 97316080327065600000 |
| 21 | 2145819571211796480000 |