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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 12 |
| 5 | 120 |
| 6 | 564 |
| 7 | 4074 |
| 8 | 25008 |
| 9 | 174618 |
| 10 | 1181100 |
| 11 | 8358306 |
| 12 | 59167872 |
| 13 | 427081512 |
| 14 | 3103408308 |
| 15 | 22797207330 |
| 16 | 168616517760 |
| 17 | 1256350493196 |