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 | 1 |
| 3 | 8 |
| 4 | 39 |
| 5 | 190 |
| 6 | 861 |
| 7 | 3943 |
| 8 | 17867 |
| 9 | 81496 |
| 10 | 372378 |
| 11 | 1709842 |
| 12 | 7879360 |
| 13 | 36454004 |
| 14 | 169239651 |
| 15 | 788311290 |
| 16 | 3683018475 |
| 17 | 17255646688 |
| 18 | 81056033636 |
| 19 | 381668479192 |
| 20 | 1801188588566 |
| 21 | 8517994717214 |
| 22 | 40360814900566 |
| 23 | 191589547228523 |
| 24 | 911009396044132 |
| 25 | 4338777661726040 |