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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 3 |
| 7 | 7 |
| 8 | 18 |
| 9 | 41 |
| 10 | 123 |
| 11 | 367 |
| 12 | 1288 |
| 13 | 4878 |
| 14 | 19536 |
| 15 | 85263 |
| 16 | 379799 |
| 17 | 1769979 |
| 18 | 8400285 |
| 19 | 40619385 |
| 20 | 199631989 |
| 21 | 990623857 |
| 22 | 4976016485 |
| 23 | 25182878921 |
| 24 | 128564665125 |