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 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 147456 |
| 9 | 3265920 |
| 10 | 129024000 |
| 11 | 1097712000 |
| 12 | 12939264000 |
| 13 | 66784798080 |
| 14 | 436483031040 |
| 15 | 1669619952000 |
| 16 | 7629571031040 |
| 17 | 23828156352000 |
| 18 | 85476013572096 |
| 19 | 230333593351680 |
| 20 | 693478195200000 |
| 21 | 1669577821632000 |