Question

-2,1,-5,7,-17,31的规律

Answer 1

1=2^1-1
5=2^2+1
7=2^3-1
17=2^4+1
31=2^5-1
65=2^6+1
2^n+(-1)^n
-1,5,-7,17,-31,65
就是奇数上面乘以-1
也就是
an=（2^n+(-1)^n）*(-1)^n