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 | 3 |
| 6 | 5 |
| 7 | 11 |
| 8 | 29 |
| 9 | 80 |
| 10 | 222 |
| 11 | 630 |
| 12 | 1881 |
| 13 | 6004 |
| 14 | 20420 |
| 15 | 72979 |
| 16 | 270659 |
| 17 | 1035590 |
| 18 | 4087205 |
| 19 | 16675630 |
| 20 | 70440641 |
| 21 | 307933393 |
| 22 | 1390117953 |
| 23 | 6462787357 |
| 24 | 30871458702 |
| 25 | 151298796000 |
| 26 | 760250325004 |
| 27 | 3915477534861 |
| 28 | 20662363081756 |
| 29 | 111662169790416 |
| 30 | 617482470676567 |
| 31 | 3490973387652861 |