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 | 1 |
| 3 | 0 |
| 4 | 4 |
| 5 | 4 |
| 6 | 30 |
| 7 | 51 |
| 8 | 230 |
| 9 | 170 |
| 10 | 657 |
| 11 | 216347 |
| 12 | 3009722 |
| 13 | 16603784 |
| 14 | 288244979 |
| 15 | 4566061654 |
| 16 | 192922096576 |
| 17 | 20592039889787 |
| 18 | 854140717540139 |
| 19 | 7734073644382760578105 |