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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 18 |
| 7 | 381 |
| 8 | 7601 |
| 9 | 160784 |
| 10 | 3621067 |
| 11 | 87089383 |
| 12 | 2235081950 |
| 13 | 61129825519 |
| 14 | 1778536033055 |
| 15 | 54930050817476 |
| 16 | 1796853497380257 |
| 17 | 62110926582550043 |
| 18 | 2263534922105574576 |
| 19 | 86779223311878261139 |
| 20 | 3492564794206986891273 |
| 21 | 147269976213917444452508 |