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) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 16 |
| 7 | 56 |
| 8 | 189 |
| 9 | 616 |
| 10 | 1967 |
| 11 | 6182 |
| 12 | 19205 |
| 13 | 59124 |
| 14 | 180726 |
| 15 | 549276 |
| 16 | 1661646 |
| 17 | 5007520 |
| 18 | 15042722 |
| 19 | 45068836 |
| 20 | 134727499 |
| 21 | 401991436 |
| 22 | 1197519631 |
| 23 | 3562523314 |
| 24 | 10585937404 |
| 25 | 31424706800 |
| 26 | 93206486620 |
| 27 | 276253350360 |
| 28 | 818278951035 |
| 29 | 2422518642516 |