projecteuler.net Problem 21: Amicable numbers. A JavaScript solution.

amicable.js

/*
projecteuler.net
Amicable numbers
Problem 21
Let d(n) be defined as the sum of proper divisors of n (numbers less than n which divide evenly into n).
If d(a) = b and d(b) = a, where a ≠ b, then a and b are an amicable pair and each of a and b are called amicable numbers.

For example, the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110; therefore d(220) = 284. The proper divisors of 284 are 1, 2, 4, 71 and 142; so d(284) = 220.

Evaluate the sum of all the amicable numbers under 10000.
*/

var total = 10000;
var halfTotal = total / 2;
var amicableNumbers = [];
var sum = 0;

for (var i = 0; i < halfTotal; i++){
  if (total % i === 0){
    amicableNumbers.push(i);
    sum += i;
  }
}

console.log("Sum of all amicable numbers under " + total + " is " + sum);
console.log(amicableNumbers);