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 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 12 |
| 5 | 61 |
| 6 | 301 |
| 7 | 1460 |
| 8 | 7019 |
| 9 | 33628 |
| 10 | 160934 |
| 11 | 770109 |
| 12 | 3686706 |
| 13 | 17661288 |
| 14 | 84675601 |
| 15 | 406319271 |
| 16 | 1951428049 |
| 17 | 9380072046 |
| 18 | 45124798445 |
| 19 | 217252113080 |
| 20 | 1046731684143 |
| 21 | 5046754081095 |
| 22 | 24348794377704 |
| 23 | 117547968556766 |
| 24 | 567818803946292 |
| 25 | 2744396907325759 |