Germain Primes

germain-primes.clj

;; http://stackoverflow.com/questions/1590716/clojure-prime-numbers-lazy-sequence
(def primes
  (let [primes (atom [])]
    (for [n (iterate inc 2)
          :when (not-any? #(zero? (rem n %))
                          (filter #(<= % (Math/sqrt n))
                                  @primes))]
      (do (swap! primes conj n)
          n))))

;; http://blog.marrowboy.co.uk/2011/02/03/implementing-is-prime-n-in-clojure-using-uncle-bobs-improved-transformation-priority-list
(defn is-prime? [n]
  (if (= n 1) false
    (every? false?
      (map #(= 0 (mod n %1)) (range 2 n)))))

;; Hey look... finally some code I wrote. I know... it's wicked sweet.
(def germain-primes
  (filter #(is-prime? (inc (* 2 %))) primes))