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 | 8 |
| 5 | 42 |
| 6 | 215 |
| 7 | 964 |
| 8 | 4336 |
| 9 | 18490 |
| 10 | 78920 |
| 11 | 327422 |
| 12 | 1361450 |
| 13 | 5561651 |
| 14 | 22748172 |
| 15 | 92064605 |
| 16 | 372730314 |
| 17 | 1498785098 |
| 18 | 6028277742 |
| 19 | 24137078144 |
| 20 | 96650940881 |
| 21 | 385889337069 |
| 22 | 1540641044744 |
| 23 | 6139148609668 |
| 24 | 24462365837156 |
| 25 | 97350374411004 |
| 26 | 387401219371335 |