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 | 2 |
| 2 | 10 |
| 3 | 50 |
| 4 | 266 |
| 5 | 1452 |
| 6 | 8073 |
| 7 | 45460 |
| 8 | 258434 |
| 9 | 1479986 |
| 10 | 8525205 |
| 11 | 49342636 |
| 12 | 286721450 |
| 13 | 1671668520 |
| 14 | 9774222930 |
| 15 | 57291319170 |
| 16 | 336537958394 |
| 17 | 1980643375180 |
| 18 | 11676498649312 |
| 19 | 68940592625476 |
| 20 | 407593403738856 |
| 21 | 2412749904577020 |