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 | 1 |
| 2 | 10 |
| 3 | 57 |
| 4 | 260 |
| 5 | 1055 |
| 6 | 3990 |
| 7 | 14413 |
| 8 | 50440 |
| 9 | 172539 |
| 10 | 580250 |
| 11 | 1926089 |
| 12 | 6328140 |
| 13 | 20619703 |
| 14 | 66732190 |
| 15 | 214742085 |
| 16 | 687698960 |
| 17 | 2193154547 |
| 18 | 6968850210 |
| 19 | 22073006401 |
| 20 | 69714716500 |
| 21 | 219623377071 |
| 22 | 690291036710 |