006.clj

; Problem 6: Sum square difference
; The sum of the squares of the first ten natural numbers is,

; 12 + 22 + ... + 102 = 385
; The square of the sum of the first ten natural numbers is,

; (1 + 2 + ... + 10)2 = 552 = 3025
; Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640.

; Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.

(defn difference [n]
  (let [squares-sum (apply + (map #(* % %) (range 1 (inc n))))
        sums-square (#(* % %) (apply + (range 1 (inc n))))]
    (- sums-square squares-sum)))

(difference 100) ; 25164150