Project Euler Problem 2 - Even Fibonacci numbers

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.

max = 4000000
sum = 0

a = 1
b = 2

while(b <= max):
sum += b
a += b * 2
b = a * 2 - b

print sum