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 | 0 |
| 5 | 1680 |
| 6 | 27342 |
| 7 | 208302 |
| 8 | 1099602 |
| 9 | 4636072 |
| 10 | 16734438 |
| 11 | 53810484 |
| 12 | 158053119 |
| 13 | 431305959 |
| 14 | 1106791524 |
| 15 | 2694914978 |
| 16 | 6269281305 |
| 17 | 14010246285 |
| 18 | 30208869495 |
| 19 | 63074014815 |
| 20 | 127909521180 |
| 21 | 252581107180 |
| 22 | 486738385140 |