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 | 0 |
| 4 | 0 |
| 5 | 4 |
| 6 | 48 |
| 7 | 708 |
| 8 | 9807 |
| 9 | 119436 |
| 10 | 1355400 |
| 11 | 14561360 |
| 12 | 150429819 |
| 13 | 1506841872 |
| 14 | 14732613116 |
| 15 | 141226638540 |
| 16 | 1331912032173 |
| 17 | 12390368538412 |
| 18 | 113927616087252 |
| 19 | 1037080582036632 |
| 20 | 9358430685657218 |
| 21 | 83804192879934456 |
| 22 | 745394788170961932 |
| 23 | 6590038606472968276 |