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 | 1 |
| 2 | 1 |
| 3 | 13 |
| 4 | 189 |
| 5 | 3816 |
| 6 | 88646 |
| 7 | 2013383 |
| 8 | 42040699 |
| 9 | 807900526 |
| 10 | 14537331816 |
| 11 | 249111237453 |
| 12 | 4119281678909 |
| 13 | 66371933499236 |
| 14 | 1049372070568186 |
| 15 | 16362812045380723 |
| 16 | 252561404639492319 |
| 17 | 3869204360738213946 |
| 18 | 58948921926491795756 |
| 19 | 894453362388005059193 |