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 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 32 |
| 5 | 277 |
| 6 | 3179 |
| 7 | 41799 |
| 8 | 632365 |
| 9 | 10922385 |
| 10 | 210953381 |
| 11 | 4498975425 |
| 12 | 105131807571 |
| 13 | 2672061475343 |
| 14 | 73358721633794 |
| 15 | 2163013965362752 |
| 16 | 68174082537113173 |
| 17 | 2287395123402364673 |
| 18 | 81397403660409278779 |
| 19 | 3061825168335759481187 |
| 20 | 121385088042529743488517 |
| 21 | 5058460899905730365609710 |