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 | 2 |
| 3 | 8 |
| 4 | 32 |
| 5 | 136 |
| 6 | 596 |
| 7 | 2712 |
| 8 | 12642 |
| 9 | 60234 |
| 10 | 291840 |
| 11 | 1434184 |
| 12 | 7130640 |
| 13 | 35807114 |
| 14 | 181339236 |
| 15 | 925139186 |
| 16 | 4750176056 |
| 17 | 24528421712 |
| 18 | 127294780994 |
| 19 | 663591911824 |
| 20 | 3473315219722 |
| 21 | 18246162722278 |
| 22 | 96169600405626 |
| 23 | 508413199626078 |
| 24 | 2695245063006696 |
| 25 | 14324688031734740 |