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) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 11 |
| 6 | 35 |
| 7 | 118 |
| 8 | 392 |
| 9 | 1336 |
| 10 | 4587 |
| 11 | 15986 |
| 12 | 56231 |
| 13 | 199854 |
| 14 | 716014 |
| 15 | 2584742 |
| 16 | 9390656 |
| 17 | 34315811 |
| 18 | 126039218 |
| 19 | 465062362 |
| 20 | 1723066193 |
| 21 | 6407806833 |
| 22 | 23910159818 |
| 23 | 89493721076 |
| 24 | 335912335304 |
| 25 | 1264105728831 |
| 26 | 4768446686910 |
| 27 | 18027215660947 |
| 28 | 68291877609003 |