Problem description, from Project Euler

Find the difference between the sum of the squares of the first N natural numbers and the square of the sum.

Solution

This one actually seemed to be easier than the others. No filters required!

    (defn problem06
        [upper]
        (defn sq [n] (* n n))
        (def l (range 1 (+ upper 1)))
        (- 
            (sq (reduce + l))
            (reduce + (map sq l))
            )
        )

The biggest hangup I had was that when I originally read the problem, I thought I’d need a power function, and then spent at least 15 minutes determining there was no Clojure core power function. I found some alternatives here:

 ; for integers (cuz it's faster)
 (. (. java.math.BigInteger (valueOf 2)) (pow 5))
 ; for doubles 
 (. java.lang.Math (pow 2 -3))