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 | 3 |
| 4 | 14 |
| 5 | 55 |
| 6 | 231 |
| 7 | 952 |
| 8 | 3976 |
| 9 | 16614 |
| 10 | 69750 |
| 11 | 293557 |
| 12 | 1238952 |
| 13 | 5240599 |
| 14 | 22212645 |
| 15 | 94318875 |
| 16 | 401143304 |
| 17 | 1708558480 |
| 18 | 7286677479 |
| 19 | 31113264579 |
| 20 | 132994055090 |
| 21 | 569048532612 |
| 22 | 2437033824302 |
| 23 | 10445705817063 |
| 24 | 44807461337160 |
| 25 | 192342179361800 |
| 26 | 826205908069555 |
| 27 | 3551172735996756 |
| 28 | 15272395383833658 |