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 | 2 |
| 5 | 10 |
| 6 | 4 |
| 7 | 12 |
| 8 | 32 |
| 9 | 96 |
| 10 | 144 |
| 11 | 576 |
| 12 | 2280 |
| 13 | 11988 |
| 14 | 47128 |
| 15 | 232756 |
| 16 | 1290772 |
| 17 | 7383588 |
| 18 | 46039788 |
| 19 | 311958088 |
| 20 | 2263575696 |
| 21 | 16975534432 |