sum LCM quo second arg

public class Calc {
  public static void main(String[] args) {
    try {
      int a = Integer.parseInt(args[0]);
      int b = Integer.parseInt(args[1]);
      System.out.println(calc(a, b));
    } catch (Exception e) {
      e.printStackTrace(System.err);
      System.exit(1);
    }
  }

  private static int gcd(int a, int b) {
    if (a == 0 || b == 0) {
      throw new IllegalArgumentException();
    }
    a = Math.abs(a);
    b = Math.abs(b);
    while (b > 0) {
      int c = a;
      a = b;
      b = c % b;
    }
    return a;
  }

  private static int lcm(int a, int b) {
    a = Math.abs(a);
    b = Math.abs(b);
    return a / gcd(a, b) * b;
  }

  private static int lcm_quo(int a, int b) {
    a = Math.abs(a);
    b = Math.abs(b);
    return a / gcd(a, b);
  }

  private static int calc(int a, int b) {
    int sum = 0;
    for (int i = 1; i <= a; ++i) {
      sum += lcm_quo(i, b);
    }
    return sum;
  }
}