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 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 1 |
| 7 | 4 |
| 8 | 41 |
| 9 | 1981 |
| 10 | 304496 |
| 11 | 78322916 |
| 12 | 27033154065 |
| 13 | 11934777413049 |
| 14 | 6593485023089912 |
| 15 | 4485517185017734885 |
| 16 | 3707462300996644966161 |
| 17 | 3680029088808704302571244 |
| 18 | 4341813441626431900011624077 |
| 19 | 6033239205199253768404631967656 |
| 20 | 9792722283774379198364367866020815 |