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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 15 |
| 4 | 24 |
| 5 | 120 |
| 6 | 240 |
| 7 | 840 |
| 8 | 2000 |
| 9 | 5760 |
| 10 | 14520 |
| 11 | 39600 |
| 12 | 102120 |
| 13 | 271440 |
| 14 | 706440 |
| 15 | 1860360 |
| 16 | 4860000 |
| 17 | 12752040 |
| 18 | 33356160 |
| 19 | 87403800 |
| 20 | 228750960 |
| 21 | 599073720 |
| 22 | 1568199600 |
| 23 | 4106118240 |
| 24 | 10749438000 |
| 25 | 28143753000 |
| 26 | 73679945040 |
| 27 | 192900147840 |
| 28 | 505015608720 |
| 29 | 1322157322200 |
| 30 | 3461443490760 |