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 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 15 |
| 5 | 110 |
| 6 | 1080 |
| 7 | 13377 |
| 8 | 200704 |
| 9 | 3542940 |
| 10 | 72000000 |
| 11 | 1656409535 |
| 12 | 42568187904 |
| 13 | 1208912928522 |
| 14 | 37603105146880 |
| 15 | 1271514111328125 |
| 16 | 46443371157258240 |
| 17 | 1822442358054692408 |
| 18 | 76461926986744528896 |
| 19 | 3415753581721829617275 |