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 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 192 |
| 5 | 1800 |
| 6 | 103680 |
| 7 | 529200 |
| 8 | 232243200 |
| 9 | 8230118400 |
| 10 | 1463132160000 |
| 11 | 39833773056000 |
| 12 | 20858412072960000 |
| 13 | 1615657835151360000 |
| 14 | 584619573580922880000 |
| 15 | 1908495817772544000000 |
| 16 | 29184209113159670169600000 |
| 17 | 3953548328298349068288000000 |
| 18 | 185476873609942457647104000000 |