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 | 30 |
| 2 | 420 |
| 3 | 4200 |
| 4 | 34650 |
| 5 | 252252 |
| 6 | 1681680 |
| 7 | 10501920 |
| 8 | 62355150 |
| 9 | 355655300 |
| 10 | 1963217256 |
| 11 | 10546208400 |
| 12 | 55367594100 |
| 13 | 285028443000 |
| 14 | 1442592936000 |
| 15 | 7193730107520 |
| 16 | 35406640372950 |
| 17 | 172255143129300 |
| 18 | 829376615067000 |