import java.util.TreeSet;

public class Euler203 {
    public static void main(String[] args) {
        int rows = 51;
        TreeSet<Long> values = new TreeSet<>();
        for (int n = 0; n < rows; n++) {
            long c = 1;
            for (int k = 0; k <= n; k++) {
                values.add(c);
                if (k < n)
                    c = c * (n - k) / (k + 1);
            }
        }
        long sum = 0;
        for (long v : values)
            if (isSquarefree(v))
                sum += v;
        System.out.println(sum);
    }

    static boolean isSquarefree(long v) {
        if (v == 0)
            return false;
        if (v % 4 == 0)
            return false;
        for (long p = 3; p * p <= v; p += 2)
            if (v % (p * p) == 0)
                return false;
        return true;
    }
}