fib.c

#include <stdio.h>

static unsigned long count;
static unsigned long fib(unsigned n) {
	++count;
	return n > 1 ? fib(n - 1) + fib(n - 2) : n;
}

int main(void) {
	unsigned i;
	for (i = 0; i < 36; ++i) {
		unsigned long ans;
		count = 0;
		ans = fib(i);
		printf("%2u: %10u (%10u calls)\n", i, ans, count);
	}
	return 0;
}