Euler 2

欧拉项目第二题：

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:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

Answer:

4613732

a, b = 1, 1
sum = 0
while b < 4000000 :
    if b%2 == 0:
        sum += b
    a, b = b, a + b
print sum