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 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 126 |
| 4 | 4284 |
| 5 | 235620 |
| 6 | 19085220 |
| 7 | 2137544640 |
| 8 | 316356606720 |
| 9 | 59791398670080 |
| 10 | 14050978687468800 |
| 11 | 4018579904616076800 |
| 12 | 1374354327378698265600 |
| 13 | 553864793933615401036800 |
| 14 | 259762588354865623086259200 |
| 15 | 140271797711627436466579968000 |
| 16 | 86407427390362500863413260288000 |