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 | 16 |
| 5 | 4450 |
| 6 | 442980 |
| 7 | 11281312 |
| 8 | 139580160 |
| 9 | 1103589198 |
| 10 | 6433276500 |
| 11 | 30047250222 |
| 12 | 118507673088 |
| 13 | 408912072478 |
| 14 | 1265701033492 |
| 15 | 3579712962750 |
| 16 | 9380986518528 |
| 17 | 23027843919870 |
| 18 | 53409035159316 |
| 19 | 117860600410206 |
| 20 | 248890790976000 |
| 21 | 505371757001454 |
| 22 | 990655558290772 |