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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 8 |
| 4 | 48 |
| 5 | 384 |
| 6 | 4480 |
| 7 | 59520 |
| 8 | 897792 |
| 9 | 15368192 |
| 10 | 293769216 |
| 11 | 6198589440 |
| 12 | 143130972160 |
| 13 | 3590253477888 |
| 14 | 97214510235648 |
| 15 | 2826205634330624 |
| 16 | 87801981951344640 |
| 17 | 2902989352269250560 |
| 18 | 101776549707306237952 |
| 19 | 3771425415371470405632 |
| 20 | 147285455218020210180096 |