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 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 39 |
| 4 | 417 |
| 5 | 5685 |
| 6 | 94365 |
| 7 | 1847475 |
| 8 | 41686785 |
| 9 | 1065288105 |
| 10 | 30411314325 |
| 11 | 959236098975 |
| 12 | 33129890726625 |
| 13 | 1243507150410525 |
| 14 | 50401090111697325 |
| 15 | 2193907232242600875 |
| 16 | 102075654396429338625 |
| 17 | 5055304328553234380625 |
| 18 | 265522264682686831945125 |
| 19 | 14742355948224269570580375 |