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 | 0 |
| 3 | 1 |
| 4 | 5 |
| 5 | 37 |
| 6 | 366 |
| 7 | 4553 |
| 8 | 68408 |
| 9 | 1206405 |
| 10 | 24447440 |
| 11 | 560041201 |
| 12 | 14315792256 |
| 13 | 404057805989 |
| 14 | 12482986261760 |
| 15 | 419042630871225 |
| 16 | 15189786100468736 |
| 17 | 591374264243364037 |
| 18 | 24612549706061862912 |
| 19 | 1090556290466098198625 |