Number Two

Python shines on this one. Find the sum of all the even-valued terms in the Fibonacci sequence which do not exceed four million.

from itertools import ifilterfalse

def fib(n1=1,n2=1,fmax=4000000):
    "terminating fibonacci sequence"

    assert 0 < n1 <= n2 < fmax
    l = [n2,n1]
    while l:
        if l[0] < fmax/2:
            l.append(sum(l))
        yield l.pop(0)

if __name__ == "__main__":
    print sum(ifilterfalse(lambda x: x % 2,fib()))