Problem 25

Problem 25
Filename: prob25.c

/* Prob 25
 * The Fibonacci sequence is defined by the recurrence relation:
 * 
 * Fn = Fn1 + Fn2, 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?
 */

module Prob2
    where
      fibs = 0 : 1: [a+b | (a,b) <- zip fibs (tail fibs)]
      answer = sum (filter even (takeWhile (length) fibs)

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