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 | 4 |
| 5 | 10 |
| 6 | 26 |
| 7 | 73 |
| 8 | 213 |
| 9 | 645 |
| 10 | 2007 |
| 11 | 6391 |
| 12 | 20741 |
| 13 | 68407 |
| 14 | 228753 |
| 15 | 774162 |
| 16 | 2647548 |
| 17 | 9138342 |
| 18 | 31802118 |
| 19 | 111489492 |
| 20 | 393442848 |
| 21 | 1396771812 |
| 22 | 4985732628 |
| 23 | 17884908282 |
| 24 | 64449398994 |
| 25 | 233220788850 |
| 26 | 847211744806 |
| 27 | 3088649627798 |