The Fibonacci sequence is defined by the recurrence relation:

Fn = Fn−1 + Fn−2, where F1 = 1 and F2 = 1.
Hence the first 12 terms will be:

F1 = 1
F2 = 1
F3 = 2
F4 = 3
F5 = 5
F6 = 8
F7 = 13
F8 = 21
F9 = 34
F10 = 55
F11 = 89
F12 = 144
The 12th term, F12, is the first term to contain three digits.

What is the first term in the Fibonacci sequence to contain 1000 digits?

https://projecteuler.net/problem=25

def fib():
  count = 2
  a = 1
  b = 1
  test = 1
  while True:
    count += 1
    test = a + b
    if len(str(test)) == 1000:
        return count
    a = b
    b = test

result = fib()
print "The first term in the Fibonacci sequence to contain 1000 digits is: %r" % result