User:Jay Gatsby/sandbox

This is Jay Gatsby's sandbox.

=Reduced residue system= A reduced residue system modulo n is a set of $$\phi$$(n) integers such that each integer is relatively prime to n and no two are congruent modulo n. Here $$\phi$$ denotes Euler's totient function.

Facts

 * If {r1, r2, ..., r$\phi$(n)} is a reduced residue system with n > 2, then $$\sum r_i=0$$ (mod n).