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) |
|---|---|
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 24 |
| 6 | 85 |
| 7 | 286 |
| 8 | 1008 |
| 9 | 3536 |
| 10 | 12618 |
| 11 | 45220 |
| 12 | 163504 |
| 13 | 594320 |
| 14 | 2173197 |
| 15 | 7983990 |
| 16 | 29465440 |
| 17 | 109174560 |
| 18 | 405995326 |
| 19 | 1514797020 |
| 20 | 5669021488 |
| 21 | 21275014800 |
| 22 | 80047272578 |
| 23 | 301892460012 |
| 24 | 1141069157408 |
| 25 | 4321730134624 |
| 26 | 16399422757300 |