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 | 3 |
| 4 | 9 |
| 5 | 35 |
| 6 | 195 |
| 7 | 1218 |
| 8 | 9184 |
| 9 | 75492 |
| 10 | 724995 |
| 11 | 7428905 |
| 12 | 86414559 |
| 13 | 1059030297 |
| 14 | 14455096201 |
| 15 | 206132138310 |
| 16 | 3228219898080 |
| 17 | 52501425954872 |
| 18 | 927663133292361 |
| 19 | 16944154401198843 |
| 20 | 333387373140423145 |
| 21 | 6756756713150677275 |
| 22 | 146490980301083247291 |