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 | 6 |
| 2 | 22 |
| 3 | 80 |
| 4 | 294 |
| 5 | 1092 |
| 6 | 4092 |
| 7 | 15444 |
| 8 | 58630 |
| 9 | 223652 |
| 10 | 856596 |
| 11 | 3292016 |
| 12 | 12688732 |
| 13 | 49031400 |
| 14 | 189885240 |
| 15 | 736808220 |
| 16 | 2863971270 |
| 17 | 11149451940 |
| 18 | 43465121700 |
| 19 | 169657266240 |
| 20 | 662976162420 |
| 21 | 2593424304120 |
| 22 | 10154564564040 |
| 23 | 39794915183400 |
| 24 | 156078401826204 |
| 25 | 612605246582952 |