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 | 1 |
| 5 | 0 |
| 6 | 1 |
| 7 | 2 |
| 8 | 3 |
| 9 | 8 |
| 10 | 20 |
| 11 | 55 |
| 12 | 161 |
| 13 | 478 |
| 14 | 1496 |
| 15 | 4804 |
| 16 | 15589 |
| 17 | 51377 |
| 18 | 172162 |
| 19 | 583810 |
| 20 | 1998407 |