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 | -120 |
| 2 | 5400 |
| 3 | -104160 |
| 4 | 511800 |
| 5 | 6770736 |
| 6 | -19504800 |
| 7 | -452207040 |
| 8 | -2959622280 |
| 9 | -12932941080 |
| 10 | -44497080432 |
| 11 | -129918587040 |
| 12 | -335811977760 |
| 13 | -788655411600 |
| 14 | -1714912983360 |
| 15 | -3498061536576 |
| 16 | -6761506680840 |
| 17 | -12481939678320 |
| 18 | -22138262633160 |
| 19 | -37922739116640 |