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 | 9 |
| 10 | 23 |
| 11 | 62 |
| 12 | 188 |
| 13 | 574 |
| 14 | 1826 |
| 15 | 5953 |
| 16 | 19664 |
| 17 | 66049 |
| 18 | 224700 |
| 19 | 771859 |
| 20 | 2674753 |