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.

(ns euler002
  (:require [cljs.test :refer-macros [deftest is run-tests]]))

(def fibo (lazy-cat [0 1] (map + fibo (rest fibo))))

(defn euler-002 [n]
  (->> fibo
       (filter even?)
       (take-while #(< % n))
       (reduce +)))

(euler-002 4000000)