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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 15 |
| 5 | 58 |
| 6 | 232 |
| 7 | 954 |
| 8 | 4010 |
| 9 | 17156 |
| 10 | 74469 |
| 11 | 327168 |
| 12 | 1452075 |
| 13 | 6501156 |
| 14 | 29326743 |
| 15 | 133166064 |
| 16 | 608188737 |
| 17 | 2791992736 |
| 18 | 12876049123 |
| 19 | 59626721244 |
| 20 | 277150709717 |
| 21 | 1292583258866 |
| 22 | 6046985696778 |
| 23 | 28369001791034 |
| 24 | 133436435891480 |