Given parameters a,b,c; max(a,b,c)≤9000. Your task is to compute a∑x=1b∑y=1c∑z=1d(x∗y∗z) by modulo 230 where d(n) is the divisor count function : the number of positive divisors of n.
This is the final problem in my recent OI Mocktest, I can only solve it to the first subtask: max(a,b,c)≤200, by iterating over all triplets (x,y,z) and adding d(x∗y∗z) to the result variable, to compute d(x∗y∗z), I used applied prime sieve.
Can you suggest the algorithm for the final subtask?
Any help would be highly appreciated!