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 | 3 |
| 4 | 56 |
| 5 | 511 |
| 6 | 194 |
| 7 | 46976 |
| 8 | 104633 |
| 9 | 546681 |
| 10 | 41130177 |
| 11 | 643108140 |
| 12 | 7034542959 |
| 13 | 65748733699 |
| 14 | 1518781632657 |
| 15 | 35097481516962 |
| 16 | 396029533782911 |
| 17 | 4146710666095789 |
| 18 | 159899356955923308 |
| 19 | 3662069108121609141 |
| 20 | 109629928744379590001 |
| 21 | 828180977946159463007 |