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 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 5 |
| 5 | 16 |
| 6 | 65 |
| 7 | 260 |
| 8 | 1085 |
| 9 | 4600 |
| 10 | 19845 |
| 11 | 86725 |
| 12 | 383251 |
| 13 | 1709566 |
| 14 | 7687615 |
| 15 | 34812519 |
| 16 | 158614405 |
| 17 | 726612216 |
| 18 | 3344696501 |
| 19 | 15462729645 |
| 20 | 71763732545 |
| 21 | 334236300200 |
| 22 | 1561686608685 |
| 23 | 7318223046860 |
| 24 | 34386154568375 |
| 25 | 161970182441556 |
| 26 | 764676831501575 |
| 27 | 3617755131480841 |