raposatu

My (sloppy) attempt at homework:

pyths hyp = [ (c1, c2) | c1 <- [1..hyp-1], c2 <- [1..hyp-1], c1*c1 + c2*c2 == hyp*hyp ] perfects n = [ x | x <- [1..n], x == sum (f x) ] where f n = [ x | x <- [1..n-1], n `mod` x == 0 ] scalarProd xs ys = sum [ x*y | (x, ix) <- zip xs
 [1..], (y, iy) <- zip ys [1..], ix == iy] scalarProd_map xs ys = sum (map (\(x, y) -> x * y) (zip xs ys))

Why freaky? (k*3)^2 + (k*4)^2 = (k*5)^2.