def fib(n, c={0:1, 1:1}):
    if n not in c:
        x = n // 2
        c[n] = fib(x-1) * fib(n-x-1) + fib(x) * fib(n - x)
    return c[n]

fib(10000000)  # calculating it takes a few seconds, printing it takes eons