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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 0 |
| 6 | 1 |
| 7 | 0 |
| 8 | 3 |
| 9 | 0 |
| 10 | 8 |
| 11 | 2 |
| 12 | 34 |
| 13 | 31 |
| 14 | 330 |
| 15 | 1607 |
| 16 | 17970 |
| 17 | 193906 |
| 18 | 2867269 |
| 19 | 32674056 |
| 20 | 1581626328 |
| 21 | 6705889815 |