
process.stdin.resume();
process.stdin.setEncoding('utf8');

var lines = []
var reader = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});

reader.on('line', (line) => {
  lines.push(line);
});

reader.on('close', () => {
 var k = Number(lines[0]);
 var one = 1;
 var two = 1;
 var three = 1;
 var ans = 0;
 var n = 0;
 
 while(n !== k){
   ans += gcd(one,two,three);
   if(one == two && two == three){
     three = three + 1;
   }else if((one == two && two !== three) && one < three){
     two = two + 1;
     three = three - 1;
   }else if((one == three && one !== two) && one < two){
     three = three + 1;
   }else if((two == three && one != two) && (one < two)){
     one = one + 1;
   }else if((two == three && one != two) && (one > two)){
     three = three + 1;
   }else if((one == three && one !== two) && (one > two)){
     two = two + 1;
     three = three - 1;
   }else if((one == two && two !== three) && (one > three)){
     three = three + 1;
   }
   
   n++;
 }
 
 console.log(ans);
 
function gcd() {
     var f = (a, b) => b ? f(b, a % b) : a
     var ans = arguments[0]
     for (var i = 1; i < arguments.length; i++) {
         ans = f(ans, arguments[i]); 
     }
     return ans;
 
 

}
 
  
 
});