Finding Ramanujan numbers

ramanujan.js

/**
 * Find all possible sum of cubes for a particular number
 * @param {Number} Number to find all sum of cube pairs
 * @return {Array} Array of sum of cubes
 */
function findAllPossiblePairs(n) {
  var doneFinding = false;
  var i = 1;
  var found = [];
  var j = Math.floor(Math.pow(n, 1/3));
  while(i <= j) {
    var sum = Math.pow(i, 3) + Math.pow(j, 3);
    if(sum === n) {
      found.push([i, j]);
      j--;
      i++;
    }
    else if(sum > n) {
      j--;
    }
    else {
      i++;
    }
  }
  return found;
}

/**
 * A Ramanujan number has exactly two sum of cube pairs.
 * @param {Number} x Number to check if it's a Ramanujan number
 */
function isRamanujan(x) {
  return findAllPossiblePairs(x).length === 2;
}

console.log(findAllPossiblePairs(1729), isRamanujan(1729));