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 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 0 |
| 10 | 0 |
| 11 | 0 |
| 12 | 1 |
| 13 | 4 |
| 14 | 20 |
| 15 | 120 |
| 16 | 836 |
| 17 | 6700 |
| 18 | 60360 |
| 19 | 603960 |
| 20 | 6646090 |
| 21 | 79773180 |
| 22 | 1037232420 |
| 23 | 14523065760 |
| 24 | 217865924620 |
| 25 | 3486094113460 |
| 26 | 59266711626080 |
| 27 | 1066844378466720 |
| 28 | 20270696788641635 |
| 29 | 405424394055173080 |
| 30 | 8514090075293512920 |