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 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 694 |
| 7 | 4580 |
| 8 | 33256 |
| 9 | 260370 |
| 10 | 2166120 |
| 11 | 18945144 |
| 12 | 172810050 |
| 13 | 1633997788 |
| 14 | 15939893003 |
| 15 | 159820729208 |
| 16 | 1641980432159 |
| 17 | 17242378256155 |
| 18 | 184674461615836 |
| 19 | 2013829450204384 |
| 20 | 22324460502429244 |
| 21 | 251250502143635615 |
| 22 | 2867467023751687892 |
| 23 | 33152272498223444540 |