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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 24 |
| 4 | 240 |
| 5 | 3080 |
| 6 | 46410 |
| 7 | 822612 |
| 8 | 16771832 |
| 9 | 387395856 |
| 10 | 9999848700 |
| 11 | 285310876620 |
| 12 | 8916095279388 |
| 13 | 302875076421528 |
| 14 | 11112006618140610 |
| 15 | 437893889060776260 |
| 16 | 18446744064162650880 |
| 17 | 827240261820996258848 |
| 18 | 39346408074801256997526 |
| 19 | 1978419655656704853586044 |