not yet fast enough , cut speed by half

CountSemiprimes

import java.util.Set;
import java.util.HashSet;
class Solution {
    public int[] solution(int N, int[] P, int[] Q) {
        // write your code in Java SE 8
        int result[]=new int [Q.length];
        for(int index=0;index<P.length;index++){     
            
            result[index]=sieve(P[index],Q[index]);;
            
        }
        return result;
    }
    public int sieve(int start,int N){
        int resultCount=0;
        Set<Integer> primemul=new HashSet<Integer>();
     int [] primes=new int[N+1]; 
     int index=2;
     while(index<=N){
         if(primes[index]==0){             
             primemul.add(index);
             int multiples=index*index;
             while(multiples<=N&&multiples>2){
                 if(primes[multiples]==0){
                primes[multiples]=index;
                 }
                 multiples+=index;
                 }
         }else{
             if(!primemul.isEmpty() && index>=start){
                        int check=(int)index/primes[index];
                        if(primemul.contains(check)){
                            resultCount++;
                        }
                    }
         }
         index++;
     }
     return resultCount;
    }
}