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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 552 |
| 5 | 29412 |
| 6 | 527654 |
| 7 | 5196928 |
| 8 | 34528698 |
| 9 | 173951172 |
| 10 | 714042302 |
| 11 | 2503447216 |
| 12 | 7744201834 |
| 13 | 21635290132 |
| 14 | 55540293510 |
| 15 | 132752090192 |
| 16 | 298491879178 |
| 17 | 636559136340 |
| 18 | 1296099575166 |
| 19 | 2533344878048 |
| 20 | 4774975629082 |
| 21 | 8712052571140 |
| 22 | 15436347060646 |
| 23 | 26634487077600 |