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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | -1296 |
| 5 | 0 |
| 6 | 303750 |
| 7 | 0 |
| 8 | -36879360 |
| 9 | 0 |
| 10 | 3157481250 |
| 11 | 0 |
| 12 | -217564322976 |
| 13 | 0 |
| 14 | 12926105848656 |
| 15 | 0 |
| 16 | -689598074880000 |
| 17 | 0 |
| 18 | 33901459248661290 |
| 19 | 0 |
| 20 | -1562983866658500000 |
| 21 | 0 |
| 22 | 68423756889802253940 |
| 23 | 0 |
| 24 | -2870422192164339671040 |
| 25 | 0 |
| 26 | 116191495035298068750000 |