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 | 1 |
| 2 | -2 |
| 3 | -9 |
| 4 | -8 |
| 5 | 40 |
| 6 | 324 |
| 7 | 280 |
| 8 | -2240 |
| 9 | -26244 |
| 10 | -22400 |
| 11 | 246400 |
| 12 | 3779136 |
| 13 | 3203200 |
| 14 | -44844800 |
| 15 | -850305600 |
| 16 | -717516800 |
| 17 | 12197785600 |
| 18 | 275499014400 |
| 19 | 231757926400 |
| 20 | -4635158528000 |
| 21 | -121495065350400 |
| 22 | -101973487616000 |
| 23 | 2345390215168000 |
| 24 | 69981157641830400 |
| 25 | 58634755379200000 |