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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 1 |
| 8 | 5 |
| 9 | 31 |
| 10 | 165 |
| 11 | 809 |
| 12 | 3759 |
| 13 | 16749 |
| 14 | 72828 |
| 15 | 311235 |
| 16 | 1311415 |
| 17 | 5445722 |
| 18 | 22237612 |
| 19 | 89039027 |
| 20 | 348676555 |
| 21 | 1332824259 |
| 22 | 4967096197 |
| 23 | 18036659429 |
| 24 | 63810587933 |
| 25 | 220001781595 |