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 | 1 |
| 3 | 4 |
| 4 | 8 |
| 5 | 540 |
| 6 | 12960 |
| 7 | 1797120 |
| 8 | 22619520 |
| 9 | 465813504 |
| 10 | 267346759680000 |
| 11 | 216218419200000 |
| 12 | 199658024013127680000 |
| 13 | 136256285631578112000000 |
| 14 | 12446179270879850496000000 |
| 15 | 34611344543529418987929600 |