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 | -528 |
| 2 | -4608 |
| 3 | 312384 |
| 4 | 3664416 |
| 5 | 21745440 |
| 6 | 86782464 |
| 7 | 276703872 |
| 8 | 741794400 |
| 9 | 1758969264 |
| 10 | 3797729280 |
| 11 | 7568097984 |
| 12 | 14222957952 |
| 13 | 25253852064 |
| 14 | 43166426112 |
| 15 | 70518360960 |
| 16 | 112406614752 |
| 17 | 172631876832 |
| 18 | 260795119104 |
| 19 | 381636168000 |
| 20 | 552633117120 |
| 21 | 778105665024 |