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 | -15 |
| 2 | 105 |
| 3 | -470 |
| 4 | 1590 |
| 5 | -4593 |
| 6 | 12160 |
| 7 | -30075 |
| 8 | 69780 |
| 9 | -153750 |
| 10 | 325728 |
| 11 | -667020 |
| 12 | 1323915 |
| 13 | -2557140 |
| 14 | 4824630 |
| 15 | -8912759 |
| 16 | 16148505 |
| 17 | -28746945 |
| 18 | 50364835 |
| 19 | -86956260 |
| 20 | 148098384 |
| 21 | -249060745 |
| 22 | 413975085 |
| 23 | -680602545 |