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 | -4 |
| 2 | 28 |
| 3 | -96 |
| 4 | 1328 |
| 5 | -4672 |
| 6 | 33472 |
| 7 | -121856 |
| 8 | 3597056 |
| 9 | -13417472 |
| 10 | 33655808 |
| 11 | -127508480 |
| 12 | 5829259264 |
| 13 | -22308732928 |
| 14 | 171393728512 |
| 15 | -660468137984 |
| 16 | 40831182635008 |
| 17 | -22589996269568 |
| 18 | 175323994652672 |
| 19 | -681560447647744 |