Katas: Reproducing Math formulas in a programming language

sequence.arithmetic.js

var arithmeticSequenceCalculator = function (first, times, difference) { 
  var a1 = parseInt(first), 
      n = parseInt(times), 
      d = parseInt(difference),
      e = 0, 
      sequence = [], 
      methods = {}; 
 
      //console.log('first:'+out,', difference:'+d,', n:'+n); // DEBUG
 
      for ( var i=0 ; i<n ; i+=1 ) {
        //console.log(i); // DEBUG
        e = a1+d*i;
        sequence.push(e);
      } 
      //console.log(sequence); // DEBUG
 
      methods.sequence = sequence;
      methods.toString = function(){ var sum=0; for(var i=0;i<sequence.length;i+=1){ sum += sequence[i]; } return sum; };
      methods.sum = methods.toString();
 
      return methods;
};