Prime Sequence Generator

public void genLists(int num) {
        int[] seq = new int[num/2];
        int seqIndex = 0;
        int prime = highestPrimes[num + 1];
        for(;;) {
            System.out.print("i");
            num -= prime;
            seq[seqIndex++] = prime;
            if(num == 0) {
                seqs.add(seq.clone());
            }
            if(num <= 0) {
                prime = -1;
            }
            while(prime < 0 && seqIndex > 0) {
                prime = seq[--seqIndex];
                seq[seqIndex] = 0;
                num += prime;
                prime = highestPrimes[prime];
            }
            if(prime < 0 && seqIndex <= 0) {
                break;
            }
        }
    }