In sagemath (version 8.1), I fail to have exp(-I*2*pi/5) ^ 5 nicely reduced to 1. I get 1/1024*(sqrt(5) - I*sqrt(2*sqrt(5) + 10) - 1)^5 instead of 1.
exp(-I*2*pi/3)^3 does not produce 1 at first, but after expand I get 1 - which I fail to obtain with exp(-I*2*pi/5)^5.
exp(-I*2*pi/15) ^ 15 does not produce 1, even after expand.
But, other expression like : exp(-I2pi/35)^35 , exp(-I2pi/18)^18 just behave as expected.
I there a way to block the evaluation of exp(-I2pi/N) when N is small ? so to keep working only with exponent ?
