(updates on the site. pagerank just hit 3 on google. hopefully this will increase traffic a bit. and this post is the first post on the site done in windows 7 (took 6 hours for my pc to update )

Problem #50 says:

The prime 41, can be written as the sum of six consecutive primes:
41 = 2 + 3 + 5 + 7 + 11 + 13

This is the longest sum of consecutive primes that adds to a prime below one-hundred.
The longest sum of consecutive primes below one-thousand that adds to a prime, contains 21 terms, and is equal to 953.
Which prime, below one-million, can be written as the sum of the most consecutive primes?

The solution below is pretty much brute force. We generate the primes and then add them together and subtract from the total items in the list of primes. then we get the total of all of the primes minus the first item in the primes list and do it over again. there’s lots of room for improvements and when I get the time I’ll post them. but for now this is what I used to get the solution. Solution provided in c#/mono.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace ProjectEuler
{
    class Program
    {
        static void Main(string[] args)
        {
            Stopwatch sw = new Stopwatch();
            sw.Start();
            ArrayList primes = GeneratePrimes(1000000);
            primes.Remove(1);
            long result = 0;
            long maxlength = 0;
            Console.WriteLine("starting check");
            for (int start = 0;start<primes.Count;start++)
            {
                long temp = 0;
                for (int i = start; i < primes.Count; i++)
                {
                    temp = temp + (long)primes[i];
                }
                for (int k = primes.Count - 1; k > start; k--)
                {
                    if (temp < 1000000 && primes.Contains(temp) && k - start >= maxlength)
                    {
                        maxlength = k -start;
                        result = temp;
                        Console.WriteLine(result);
                        break;
                    }
                    temp = temp - (long)primes[k];
                    if (temp <= start)
                        break;
                }
            }
            Console.WriteLine(result);
            Console.WriteLine(maxlength);
            Console.WriteLine(sw.Elapsed);
            Console.ReadLine();
        }
        static ArrayList GeneratePrimes(long num)
        {
            ArrayList RetValue = new ArrayList();
            RetValue.Add((long)2);
            RetValue.Add((long)3);
            long Stepper = 5;
            long Check = 1;
            while (Stepper <= num)
            {
                foreach (long i in RetValue)
                {
                    if (Stepper % i == 0)
                    {
                        Check = 0;
                        break;
                    }
                    if (Math.Sqrt(Stepper) < i)
                    {
                        break;
                    }
                }
                if (Check == 1)
                {
                    //Console.WriteLine(((float)Stepper / (float)num) * 100);
                    RetValue.Add(Stepper);
                }
                Check = 1;
                Stepper++;
                Stepper++;
            }
            return RetValue;
        }
    }
}