Catalan Numbers to mathematically verify number of combinations (http://en.wikipedia.org/wiki/Catalan_number)

catalanNumber.js

// Catalan Numbers to mathematically verify number of combinations
// E.g, the number of possible combinations of parentheses
// http://en.wikipedia.org/wiki/Catalan_number
function catalanNumber(numParens) {
  var total = 1;

  for(var i = 2; i <= numParens; i++) {
    total *= (numParens + i) / i;
  }

  return total;
}