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 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 8 |
| 6 | 18 |
| 7 | 61 |
| 8 | 170 |
| 9 | 538 |
| 10 | 1654 |
| 11 | 5344 |
| 12 | 17252 |
| 13 | 57146 |
| 14 | 190786 |
| 15 | 646305 |
| 16 | 2209050 |
| 17 | 7626164 |
| 18 | 26532732 |
| 19 | 93013852 |
| 20 | 328196780 |
| 21 | 1165060170 |
| 22 | 4158266282 |
| 23 | 14915635376 |
| 24 | 53745892932 |
| 25 | 194477856048 |
| 26 | 706436256598 |
| 27 | 2575316698792 |
| 28 | 9419568272632 |