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 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 136 |
| 5 | 1915 |
| 6 | 6336 |
| 7 | 460663 |
| 8 | 13148416 |
| 9 | 91581111 |
| 10 | 3772979200 |
| 11 | 198133379411 |
| 12 | 7608426080256 |
| 13 | 52812321503747 |
| 14 | 4709633119830016 |
| 15 | 316248789972027375 |
| 16 | 16013842065532911616 |
| 17 | 296760465891270915823 |
| 18 | 13494391336411560935424 |