 If "d" is even then the equations with "k" = 0, 2, 4, ..., "d"−2 are independent.Another independent set consists of the equations with "k" = −1, 1, 3, ..., "d"−3.If "d" is odd then the equations with "k" = −1, 1, 3, ..., "d"−2 form one independent set and the equations with "k" = −1, 0, 2, 4, ..., "d"−3 form another.