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 | 2 |
| 3 | 4033920 |
| 4 | 159894687204 |
| 5 | 301280127057920 |
| 6 | 100770286250343750 |
| 7 | 11334165274707633792 |
| 8 | 603801344040208577480 |
| 9 | 18674487128527060598784 |
| 10 | 382076301190534627489290 |
| 11 | 5650667805968496542000000 |
| 12 | 64331764646611255469788332 |
| 13 | 590498122988857695000330240 |