A lot of people have responded to 10 Scala One Liners with implementations in a lot of different languages, including clojure. My suggestion can be found in this gist but one of the one-liners are especially interesting, Sieve of Eratosthenes.
There are a lot of different versions of this algorithm. This one is translated from Miranda, an old classic from Bird & Wadler, Introduction to Functional Programming, p.175, and goes something like this:
(defn sieve [xs] (filter #(not (zero? (mod % (first xs)))) (rest xs))) (defn rsieve [xs] (map first (iterate sieve xs))) (defn primes-below [max] (take-while #(not (nil? %)) (rsieve (range 2 max))))
Unfortunately, it blows the stack for large values, but I still like this simple compact definition.