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 | 4 |
| 3 | 4 |
| 4 | -8 |
| 5 | -40 |
| 6 | -16 |
| 7 | 368 |
| 8 | 928 |
| 9 | -3296 |
| 10 | -21440 |
| 11 | 16448 |
| 12 | 461696 |
| 13 | 561536 |
| 14 | -9957632 |
| 15 | -34515200 |
| 16 | 209783296 |
| 17 | 1455022592 |
| 18 | -3803020288 |
| 19 | -57076808704 |
| 20 | 22755112960 |
| 21 | 2214428956672 |
| 22 | 3518653394944 |
| 23 | -85968709390336 |
| 24 | -326758168158208 |
| 25 | 3301044295639040 |
| 26 | 22286480662872064 |