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.


In [26]:
def fib_gen(limit):
    f = 1 
    s = 2
    while f < limit:
        yield f
        f, s = s, f + s

In [30]:
sum( i for i in fib_gen(4e+6) if i%2 == 0)


Out[30]:
4613732

In [27]:
[i for i in fib_gen(10)]


Out[27]:
[1, 2, 3, 5, 8]