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 | 1 |
| 2 | 4 |
| 3 | 40 |
| 4 | 760 |
| 5 | 23560 |
| 6 | 1083760 |
| 7 | 69360640 |
| 8 | 5895654400 |
| 9 | 642626329600 |
| 10 | 87397180825600 |
| 11 | 14507932017049600 |
| 12 | 2887078471392870400 |
| 13 | 678463440777324544000 |
| 14 | 185898982772986925056000 |
| 15 | 58744078556263868317696000 |
| 16 | 21206612358811256462688256000 |