You could do it like in article, so for every nonempty element in powerset (combinations for each length) of those numbers calculate their lcm and add or subtra

You could do it like in article, so for every nonempty element in powerset (combinations for each length) of those numbers calculate their lcm and add or subtract amount of multiplies of lcm according to length of element. So for A, B, C you have (M-number of multipliers) M(lcm(A)) + M(lcm(B)) + M(lcm(C)) - M(lcm(B,C)) - M(lcm(A,C)) - M(lcm(A,B)) + M(lcm(A,B,C))