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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 11 |
| 5 | 43 |
| 6 | 180 |
| 7 | 804 |
| 8 | 3763 |
| 9 | 18331 |
| 10 | 92330 |
| 11 | 478795 |
| 12 | 2547885 |
| 13 | 13880832 |
| 14 | 77284220 |
| 15 | 439146427 |
| 16 | 2543931619 |
| 17 | 15010717722 |
| 18 | 90154755356 |
| 19 | 550817917537 |
| 20 | 3421683388385 |
| 21 | 21601986281226 |
| 22 | 138548772267326 |
| 23 | 902439162209914 |
| 24 | 5967669851051612 |
| 25 | 40053432076016812 |