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 | 2 |
| 3 | 3 |
| 4 | 14 |
| 5 | 35 |
| 6 | 125 |
| 7 | 371 |
| 8 | 1238 |
| 9 | 3909 |
| 10 | 12847 |
| 11 | 41580 |
| 12 | 136577 |
| 13 | 447187 |
| 14 | 1473341 |
| 15 | 4855703 |
| 16 | 16053830 |
| 17 | 53138243 |
| 18 | 176233967 |
| 19 | 585202261 |
| 20 | 1945964079 |
| 21 | 6478043120 |
| 22 | 21588979876 |
| 23 | 72016891508 |
| 24 | 240452892569 |
| 25 | 803489258285 |
| 26 | 2686964354375 |
| 27 | 8991840800136 |
| 28 | 30110638705889 |