UFunction

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

double calculateU(int);

int main()
{
    int n;
    double u;
    printf("Enter n: ");
    scanf("%d", &n);
    u = calculateU(n);
    printf("U(%d) = %f\n", n, u);
    return 0;
}

double calculateU(int n)
{
    int i;
    double u = 1;
    for (i = 1; i <= n; i++)
    {
        u = 2 * sqrt(u + 1) - 1;
    }
    return u;
}