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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 0 |
| 5 | 72 |
| 6 | -320 |
| 7 | 3600 |
| 8 | -32256 |
| 9 | 344960 |
| 10 | -3926016 |
| 11 | 48625920 |
| 12 | -648243200 |
| 13 | 9270125568 |
| 14 | -141579509760 |
| 15 | 2300668418048 |
| 16 | -39642283376640 |
| 17 | 722055883161600 |
| 18 | -13863472939925504 |
| 19 | 279868860012625920 |