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 | 4 |
| 5 | 21 |
| 6 | 121 |
| 7 | 956 |
| 8 | 12043 |
| 9 | 273549 |
| 10 | 11999689 |
| 11 | 1018965561 |
| 12 | 165090921457 |
| 13 | 50502028840240 |
| 14 | 29054155623249635 |
| 15 | 31426485969192461828 |
| 16 | 64001015704512693244004 |
| 17 | 245935864153532444460997784 |
| 18 | 1787577725145611678835828915650 |
| 19 | 24637809253125004523074706811821299 |