Ряд Фибоначчи хорошо описан в книге "С++ за 21 день".

#include <iostream.h>
int s=0;
int fib (int n);

int main()
{

int n, answer;
cout << "Enter number to find: ";
cin >> n;

cout << "\n\n";

answer = fib(n);

cout << answer << " is the " << n << "th Fibonacci number\n";
cout << "\n" <<s <<"\n";
return 0;
}

int fib (int n)
{
cout << "Processing fib(" << n << ")... ";
s++;
if (n < 3 )
{
cout << "Return 1!\n";
return (1);
}
else
{
cout << "Call fib(" << n-2 << ") and fib(" << n-1 << ").\n";
return (fib(n-2) + fib (n-1));
}