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 | 3 |
| 3 | 15 |
| 4 | 105 |
| 5 | 1155 |
| 6 | 1365 |
| 7 | 19635 |
| 8 | 23205 |
| 9 | 636405 |
| 10 | 10555545 |
| 11 | 24484845 |
| 12 | 869107785 |
| 13 | 14797252681546335 |
| 14 | 92442344345566215 |
| 15 | 40334203530676690635 |
| 16 | 1451417351374223318085 |
| 17 | 6087255082617244520985 |
| 18 | 469256253416014832182075245585 |
| 19 | 1519012498286389398934397206158552189345 |