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 | 1 |
| 4 | 3 |
| 5 | 4 |
| 6 | 12 |
| 7 | 24 |
| 8 | 70 |
| 9 | 172 |
| 10 | 525 |
| 11 | 1530 |
| 12 | 5078 |
| 13 | 16994 |
| 14 | 61456 |
| 15 | 228898 |
| 16 | 895910 |
| 17 | 3617148 |
| 18 | 15130833 |
| 19 | 65084088 |
| 20 | 287828488 |
| 21 | 1304327221 |
| 22 | 6050218591 |
| 23 | 28675928883 |
| 24 | 138730847262 |
| 25 | 684300453848 |
| 26 | 3438439910436 |
| 27 | 17585597712632 |
| 28 | 91479580896616 |
| 29 | 483699938173293 |
| 30 | 2598090378779507 |