function sumPrimes(num) {
  return arguments.length!==1 ?
    num>1 ? 
      sumPrimes(num-1, arguments[1].filter(function(val){return val%num!==0;}).concat(num))        
    : 
      arguments[1].reduce(function(a,b){return a+b;})   
  :
    num>1 ? sumPrimes(num-1, [num]) : 0;  
}