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 | 5 |
| 3 | 36 |
| 4 | 350 |
| 5 | 4320 |
| 6 | 64827 |
| 7 | 1146880 |
| 8 | 23383404 |
| 9 | 540000000 |
| 10 | 13933327265 |
| 11 | 397303087104 |
| 12 | 12407264266410 |
| 13 | 421154777645056 |
| 14 | 15439814208984375 |
| 15 | 607985949695016960 |
| 16 | 25593429637028941208 |
| 17 | 1146928904801167933440 |
| 18 | 54515427164280400691709 |
| 19 | 2739404800000000000000000 |