Triangular number task

src/battle_asserts/issues/triangular_number.clj

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+(ns battle-asserts.issues.triangular-number
+  (:require [clojure.test.check.generators :as gen]))
+
+(def level :elementary)
+
+(def description "Triangular Number Sequence is generated from a pattern of dots that form a triangle.
+                  The first 5 numbers of the sequence, or dots, are: `1, 3, 6, 10, 15`
+                  This means that the first triangle has just one dot, the second one has three dots, the third one has 6 dots and so on.
+                  Write a function that gives the number of dots with its corresponding triangle number of the sequence.")
+
+(def signature
+  {:input [{:argument-name "n" :type {:name "integer"}}]
+   :output {:type {:name "integer"}}})
+
+(defn arguments-generator []
+  (gen/tuple (gen/choose 1 250)))
+
+(def test-data
+  [{:expected 1 :arguments [1]}
+   {:expected 21 :arguments [6]}
+   {:expected 23220 :arguments [215]}])
+
+(defn solution [n]
+  (int (/ (* n (inc n)) 2)))