gistfile1.txt

# For project euler #2 -- http://projecteuler.net/index.php?section=problems&id=2

def fib(n)
    @result ||= []
    @result[n] ||= begin
        if n <= 1
            n
        else
            fib(n-1) + fib(n-2)
        end
    end
end

n = 1
sum = 0
f = 0
while f <= 4e6
    f = fib(n)
    sum += f if f.even?
    n += 1
end
puts sum