http://projecteuler.net/index.php?section=problems&id=73 速くなる書き方もあるが、ここは題意を素直に表現。 count_numerator d = length (filter (\n -> gcd d n == 1) [(div d 3)+1..div (d-1) 2]) main = print (sum (map count_numerator [1..12000]…