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 | 2 |
| 2 | 0 |
| 3 | 16 |
| 4 | -32 |
| 5 | 336 |
| 6 | -1472 |
| 7 | 10944 |
| 8 | -63744 |
| 9 | 441088 |
| 10 | -2866688 |
| 11 | 19772416 |
| 12 | -134832128 |
| 13 | 941381632 |
| 14 | -6585720832 |
| 15 | 46607831040 |
| 16 | -331406262272 |
| 17 | 2373110628352 |
| 18 | -17072541007872 |
| 19 | 123438375763968 |
| 20 | -896088779128832 |
| 21 | 6530356893777920 |
| 22 | -47752086733717504 |