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 | 528 |
| 12 | 1712 |
| 13 | 7472 |
| 14 | 24500 |
| 15 | 103536 |
| 16 | 486020 |
| 17 | 2218808 |
| 18 | 11113020 |
| 19 | 59242576 |
| 20 | 342584556 |
| 21 | 1981826412 |