Added (not yet working) code for #540.

project.clj

@@ -4,4 +4,5 @@
   :license {:name "Eclipse Public License"
             :url "http://www.eclipse.org/legal/epl-v10.html"}
   :dependencies [[org.clojure/clojure "1.7.0"]
-                 [org.clojure/math.combinatorics "0.1.1"]])
+                 [org.clojure/math.combinatorics "0.1.1"]
+                 [org.clojure/math.numeric-tower "0.0.4"]])

src/projecteuler/p540.clj

@@ -0,0 +1,29 @@
+(ns projecteuler.core
+  (:require [clojure.math.numeric-tower :as math]))
+
+;; https://projecteuler.net/problem=540
+
+; NOT WORKING YET.
+;
+; Correct answer for P(20), incorrect for P(1000000). Dies with memory/GC error
+; when run for P(3141592653589793N).
+
+(defn- euclid-primitive [m n]
+  (let [a (- (* m m) (* n n))
+        b (* 2 m n)
+        c (+ (* m m) (* n n))]
+    (vec (sort (list a b c)))))
+(defn- get-euclid-prims [max-p]
+  (let [max-n (int (Math/sqrt (/ max-p 2)))
+        max-m (inc max-n)]
+    (loop [n 1, c #{}]
+      (cond
+       (> n max-n) c
+       :else
+       (recur (inc n)
+              (set (concat c
+                           (filter #(<= (last %) max-p)
+                                   (map #(euclid-primitive % n)
+                                        (filter #(= 1 (math/gcd % n))
+                                                (range (inc n)
+                                                       (inc max-m) 2)))))))))))