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 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 17 |
| 6 | 48 |
| 7 | 144 |
| 8 | 449 |
| 9 | 1422 |
| 10 | 4568 |
| 11 | 14893 |
| 12 | 49139 |
| 13 | 163665 |
| 14 | 549570 |
| 15 | 1858754 |
| 16 | 6326343 |
| 17 | 21651064 |
| 18 | 74462327 |
| 19 | 257219221 |
| 20 | 892047965 |
| 21 | 3104749126 |
| 22 | 10841192392 |
| 23 | 37967942203 |
| 24 | 133333407639 |
| 25 | 469405472729 |
| 26 | 1656383420850 |
| 27 | 5857371543403 |
| 28 | 20754268304707 |