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 | 2 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 40 |
| 6 | 214 |
| 7 | 1355 |
| 8 | 9940 |
| 9 | 82834 |
| 10 | 773118 |
| 11 | 7988887 |
| 12 | 90540729 |
| 13 | 1116669003 |
| 14 | 14888920041 |
| 15 | 213407853922 |
| 16 | 3272253760146 |
| 17 | 53446811415729 |
| 18 | 926411397872639 |
| 19 | 16984208960998389 |
| 20 | 328361373245968867 |