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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 7 |
| 5 | 39 |
| 6 | 237 |
| 7 | 1734 |
| 8 | 15450 |
| 9 | 165682 |
| 10 | 2102614 |
| 11 | 31015311 |
| 12 | 524013081 |
| 13 | 10030700577 |
| 14 | 215582832795 |
| 15 | 5159960081308 |
| 16 | 136564828657252 |
| 17 | 3972563571866868 |
| 18 | 126343835507748636 |
| 19 | 4372455341681750061 |
| 20 | 163953900979575446619 |
| 21 | 6635493391775352850603 |
| 22 | 288852182590324903158841 |