a Programmer's blog

import java.util.Vector;


class runner
{
	public static boolean isPrime(int n){
		if(primes.contains(n)) return true;
		double limit = Math.sqrt(n);
		for(int p: primes){
			if(p > limit) break;
			if(n % p == 0) return false;
		}
		primes.add(n);
		return true;
	}
	
	static Vector primes = new Vector();
	public static void main (String[] args) throws java.lang.Exception
	{
		long time = System.currentTimeMillis();

		primes.add(2);
		int n = 3;
		outerLoop:
		while(true){
			if(!isPrime(n) && n % 2 == 1){
				boolean found = false;
				for(int p: primes){
					if(p < n-1){
						double sqrtdiff = Math.sqrt((n-p)/2.0);
						if(Math.floor(sqrtdiff) == sqrtdiff){
							found = true;
						}
					}
				}
				
				if(!found){
					break outerLoop;
				}
			}
			n++;
		}
		
		System.out.println("n: "+n);
		
		System.out.println("time: "+(System.currentTimeMillis() - time));
	}
}