Determine the sum of all prime numbers p for which there exists no integer solution in x to the congruence
3(6x+1) == 4 mod(p).
By simple inspection, it turns out that p=2 and p=3, for which there is no integer solution in x for the congruence 3(6x+1) == 4 mod(p).
Their sum = 2 + 3 = 5