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  "name": "",
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 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:\n",
      "\n",
      "1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...\n",
      "\n",
      "By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "fib1 = 1\n",
      "fib2 = 2\n",
      "fib3 = fib1\n",
      "\n",
      "while fib2 < 10:\n",
      "    print fib1\n",
      "    fib3 = fib1\n",
      "    fib2 += fib1\n",
      "    print fib2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1\n",
        "3\n",
        "1\n",
        "4\n",
        "1\n",
        "5\n",
        "1\n",
        "6\n",
        "1\n",
        "7\n",
        "1\n",
        "8\n",
        "1\n",
        "9\n",
        "1\n",
        "10\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "fib1 = 1\n",
      "fib2 = 2\n",
      "\n",
      "while fib2 < 10:\n",
      "    fib2, fib1 = fib2 + fib1, fib2\n",
      "    print fib2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "3\n",
        "5\n",
        "8\n",
        "13\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def fib_gen(num):\n",
      "    fib1 = 0\n",
      "    fib2 = 1\n",
      "    yield fib1\n",
      "    yield fib2\n",
      "    \n",
      "    while fib2 < num:\n",
      "        fib2, fib1 = fib2 + fib1, fib2\n",
      "        yield fib2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 10
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "[i for i in fib_gen(14)]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 16,
       "text": [
        "[0, 1, 1, 2, 3, 5, 8, 13, 21]"
       ]
      }
     ],
     "prompt_number": 16
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "sum([i for i in fib_gen(4000000) if i%2 == 0])"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 15,
       "text": [
        "4613732"
       ]
      }
     ],
     "prompt_number": 15
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}