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 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 1 |
| 8 | 105 |
| 9 | 30016 |
| 10 | 11180820 |
| 11 | 5188453830 |
| 12 | 2977635137862 |
| 13 | 2099132870973600 |
| 14 | 1803595358964773088 |
| 15 | 1872726690127181663775 |
| 16 | 2329676580698022197516875 |
| 17 | 3443086402825299720403673760 |
| 18 | 5997229769947050271535917422040 |
| 19 | 12218901113752712984458458475480428 |