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 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 0 |
| 10 | 1 |
| 11 | 2 |
| 12 | 12 |
| 13 | 67 |
| 14 | 597 |
| 15 | 7134 |
| 16 | 107820 |
| 17 | 1876672 |
| 18 | 35924730 |
| 19 | 741405102 |
| 20 | 16356067055 |
| 21 | 383931363314 |