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 | -10720 |
| 2 | 46144 |
| 3 | -406944 |
| 4 | 27728000 |
| 5 | 421271200 |
| 6 | 2938887360 |
| 7 | 13857016544 |
| 8 | 50936525056 |
| 9 | 157077960480 |
| 10 | 424598062400 |
| 11 | 1035360742240 |
| 12 | 2323482102144 |
| 13 | 4869001213856 |
| 14 | 9632766324160 |
| 15 | 18144829893600 |
| 16 | 32760875409920 |
| 17 | 57003614246944 |
| 18 | 96008691963456 |
| 19 | 157097430355040 |