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 | 1 |
| 5 | 6 |
| 6 | 21 |
| 7 | 66 |
| 8 | 170 |
| 9 | 404 |
| 10 | 984 |
| 11 | 2384 |
| 12 | 5877 |
| 13 | 14459 |
| 14 | 36720 |
| 15 | 92657 |
| 16 | 234376 |
| 17 | 597082 |
| 18 | 1525209 |
| 19 | 3913689 |
| 20 | 10076194 |
| 21 | 26016985 |