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 | 9 |
| 6 | 1875 |
| 7 | 52323 |
| 8 | 695616 |
| 9 | 5840088 |
| 10 | 35715529 |
| 11 | 172520643 |
| 12 | 708871152 |
| 13 | 2517687856 |
| 14 | 8023634766 |
| 15 | 23292994812 |
| 16 | 62357664744 |
| 17 | 155765126265 |
| 18 | 367482996726 |
| 19 | 822866800569 |
| 20 | 1762214894004 |
| 21 | 3621792301059 |