https://www.colorless-sight.jp:443/wiki/?ProjectEular%2FProblem15
[[ProjectEular]] -- Problem 15 module Main (main) where main :: IO () main = print $ problem15 problem15 :: (Integral a) => a problem15 = combination 40 20 combination :: (Integral a) => a -> a -> a combination n k = div (factorial n) (factorial k * factorial (n-k)) factorial :: (Integral a) => a -> a factorial n = product [1..n]