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 | 3 |
| 4 | 0 |
| 5 | 15 |
| 6 | 90 |
| 7 | 105 |
| 8 | 2520 |
| 9 | 8505 |
| 10 | 66150 |
| 11 | 634095 |
| 12 | 3118500 |
| 13 | 40675635 |
| 14 | 285675390 |
| 15 | 2896618725 |
| 16 | 31556725200 |
| 17 | 281774718225 |
| 18 | 3691224687150 |
| 19 | 37783760189175 |
| 20 | 483465043561500 |
| 21 | 6108282465360075 |
| 22 | 76126660317858150 |
| 23 | 1102221773079151725 |
| 24 | 14598579860502838200 |