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 | 6 |
| 3 | 140 |
| 4 | 270 |
| 5 | 672 |
| 6 | 8190 |
| 7 | 30240 |
| 8 | 332640 |
| 9 | 14303520 |
| 10 | 17428320 |
| 11 | 27027000 |
| 12 | 191711520 |
| 13 | 2144862720 |
| 14 | 3506025600 |
| 15 | 5943057120 |
| 16 | 14378364000 |
| 17 | 45578332800 |
| 18 | 288662774400 |
| 19 | 505159855200 |
| 20 | 2020639420800 |
| 21 | 10680522652800 |
| 22 | 54557264361600 |