main = (print . sum_ . map_ double . upto) (1,100)

sum_ []     = 0
sum_ (x:xs) = x + sum_ xs

map_ f []     = []
map_ f (x:xs) = f x : map_ f xs

upto (m,n) = upto' m
  where
    upto' m = if m>n then [] else m : upto' (m+1)

double x = x + x