Euler 21

gistfile1.txt

#!/usr/local/bin/node

// declare an array to hold the sums of factors for all numbers below 10,000

sums = new Array();

// fill array with sums of all "proper divisors" at each i

for (i=1;i<=10000;i++)
	{
	sums[i]=0;

	for (j=1;j<i;j++)
		{
		if (i%j==0)
			{
			sums[i]+=j;
			}
		}
	}
		
// check each i to see if it has an amicable partner
// you need to make sure the partner is larger than k (otherwise you get bad pairs)

amicablesum=0;

for (k=1;k<=10000;k++)
	{
	partner = sums[k];
	if (partner > k)
		{
		if (sums[partner]==k)
			{
			console.log(k + " and " + partner + " form an amicable pair");
			amicablesum+=(k + partner);
			}
		}
	}	

console.log("sum of all pairs is " + amicablesum);