Factnum

#include<stdio.h>
int fact(int num);
int main()
{
    int n,b;
    printf("N : ");
    scanf("%d",&n);
    b=fact(n);
    printf("Sum = %d",b);
    return 0;
}

int fact(int num)
{
    if(num==0||num==1)
    return 1;
    else
    return 4+fact(num-1)+fact(num-2);
}