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 | 19 |
| 5 | 99 |
| 6 | 603 |
| 7 | 4248 |
| 8 | 34115 |
| 9 | 307875 |
| 10 | 3085203 |
| 11 | 33993870 |
| 12 | 408482695 |
| 13 | 5316309607 |
| 14 | 74499953255 |
| 15 | 1118421967520 |
| 16 | 17907571955927 |
| 17 | 304619809031127 |
| 18 | 5486197279305911 |
| 19 | 104289196264058030 |
| 20 | 2086706157642260387 |
| 21 | 43838287730208552691 |
| 22 | 964790364323910060691 |