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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 13 |
| 4 | 222 |
| 5 | 2585 |
| 6 | 25830 |
| 7 | 238833 |
| 8 | 2111382 |
| 9 | 18142585 |
| 10 | 152937510 |
| 11 | 1271964353 |
| 12 | 10476007542 |
| 13 | 85662034185 |
| 14 | 696700867590 |
| 15 | 5643519669073 |
| 16 | 45575393343702 |
| 17 | 367206720319385 |
| 18 | 2953481502692070 |
| 19 | 23723872215168993 |
| 20 | 190372457332919862 |