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) |
|---|---|
| 3 | 1 |
| 4 | 4 |
| 5 | 19 |
| 6 | 107 |
| 7 | 702 |
| 8 | 5274 |
| 9 | 44712 |
| 10 | 422568 |
| 11 | 4407120 |
| 12 | 50292720 |
| 13 | 623471040 |
| 14 | 8344624320 |
| 15 | 119938250880 |
| 16 | 1842662908800 |
| 17 | 30136443724800 |
| 18 | 522780938265600 |
| 19 | 9587900602828800 |
| 20 | 185371298306611200 |
| 21 | 3768248516336640000 |
| 22 | 80349669847157760000 |
| 23 | 1793238207723325440000 |
| 24 | 41806479141525288960000 |