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 | 6 |
| 2 | 24 |
| 3 | 120 |
| 4 | 480 |
| 5 | 2002 |
| 6 | 7952 |
| 7 | 31824 |
| 8 | 125760 |
| 9 | 497420 |
| 10 | 1960464 |
| 11 | 7726160 |
| 12 | 30418752 |
| 13 | 119759850 |
| 14 | 471424160 |
| 15 | 1855967520 |
| 16 | 7307828352 |
| 17 | 28781143380 |
| 18 | 113380093840 |
| 19 | 446775310800 |
| 20 | 1761038703424 |
| 21 | 6943526580276 |
| 22 | 27385654785504 |