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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 5 |
| 7 | 22 |
| 8 | 90 |
| 9 | 342 |
| 10 | 1247 |
| 11 | 4491 |
| 12 | 16095 |
| 13 | 57906 |
| 14 | 209170 |
| 15 | 760830 |
| 16 | 2784913 |
| 17 | 10262649 |
| 18 | 38051063 |
| 19 | 141914613 |
| 20 | 532131882 |
| 21 | 2005320952 |
| 22 | 7591794561 |
| 23 | 28863820538 |
| 24 | 110172051829 |
| 25 | 422060152511 |
| 26 | 1622369728951 |