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 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 52 |
| 6 | 229 |
| 7 | 1024 |
| 8 | 4749 |
| 9 | 22454 |
| 10 | 108299 |
| 11 | 529896 |
| 12 | 2625903 |
| 13 | 13148268 |
| 14 | 66428383 |
| 15 | 338197609 |
| 16 | 1733399552 |
| 17 | 8936746984 |
| 18 | 46315049443 |
| 19 | 241146306914 |
| 20 | 1260805087503 |
| 21 | 6616786338256 |
| 22 | 34843842405490 |
| 23 | 184057255372576 |