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 | 4 |
| 2 | 68 |
| 3 | 1224 |
| 4 | 21960 |
| 5 | 394060 |
| 6 | 7071116 |
| 7 | 126886032 |
| 8 | 2276877456 |
| 9 | 40856908180 |
| 10 | 733147469780 |
| 11 | 13155797547864 |
| 12 | 236071208391768 |
| 13 | 4236125953503964 |
| 14 | 76014195954679580 |
| 15 | 1364019401230728480 |
| 16 | 24476335026198433056 |
| 17 | 439210011070341066532 |