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 | 240 |
| 2 | 9120 |
| 3 | 121680 |
| 4 | 864960 |
| 5 | 4113840 |
| 6 | 14905440 |
| 7 | 44480400 |
| 8 | 114879360 |
| 9 | 265422960 |
| 10 | 561403680 |
| 11 | 1105317840 |
| 12 | 2050966080 |
| 13 | 3620750640 |
| 14 | 6126497760 |
| 15 | 9994133520 |
| 16 | 15792541440 |
| 17 | 24266930160 |
| 18 | 36377039520 |
| 19 | 53340513360 |
| 20 | 76681767360 |