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 | 3 |
| 5 | 5 |
| 6 | 17 |
| 7 | 40 |
| 8 | 138 |
| 9 | 430 |
| 10 | 1546 |
| 11 | 5478 |
| 12 | 20525 |
| 13 | 77310 |
| 14 | 298301 |
| 15 | 1161692 |
| 16 | 4583525 |
| 17 | 18239037 |
| 18 | 73221198 |
| 19 | 296046399 |
| 20 | 1205038270 |
| 21 | 4933969005 |
| 22 | 20311807087 |
| 23 | 84029440358 |
| 24 | 349201537324 |
| 25 | 1457205298510 |
| 26 | 6104204225832 |
| 27 | 25661191956781 |
| 28 | 108231773165825 |