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 | 1 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 4 |
| 8 | 20 |
| 9 | 20 |
| 10 | 0 |
| 11 | 16 |
| 12 | 200 |
| 13 | 1120 |
| 14 | 3540 |
| 15 | 6864 |
| 16 | 9400 |
| 17 | 18240 |
| 18 | 82000 |
| 19 | 364256 |
| 20 | 1255040 |
| 21 | 3448400 |
| 22 | 8094400 |
| 23 | 18653984 |
| 24 | 50789120 |
| 25 | 166596240 |
| 26 | 565558400 |
| 27 | 1791310496 |
| 28 | 5202559520 |
| 29 | 14279014880 |
| 30 | 39040502400 |
| 31 | 111437733184 |
| 32 | 335085082880 |
| 33 | 1032287357600 |