Sieve of Eratosthenes in Clojure (first attempt, undoubtedly can be improved)

primes.clj

(ns kmr.primes
  (:use clojure.set))

(defn eratos
  "Compute all primes below n using Sieve of Eratosthenes."
  [n]
  (loop [i 2 
         sieve (set (range 2 (inc n)))]
    (if (> (* i i) n)
      sieve
      (recur (first (drop-while #(not (contains? sieve %)) (range (inc i) n)))
             (difference sieve (set (range (+ i i) (inc n) i)))))))

(= (sort (eratos 100)) '(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97))