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 | 0 |
| 3 | 0 |
| 4 | 48 |
| 5 | 528 |
| 6 | 4752 |
| 7 | 44080 |
| 8 | 408192 |
| 9 | 3738692 |
| 10 | 32818416 |
| 11 | 282587664 |
| 12 | 2417602560 |
| 13 | 20523442012 |
| 14 | 172798010156 |
| 15 | 1443679767220 |
| 16 | 11992713950224 |
| 17 | 99165736820120 |
| 18 | 816514750434924 |
| 19 | 6697254233908596 |
| 20 | 54745726513283448 |
| 21 | 446174778295639204 |
| 22 | 3626566397497170096 |