-- Find the sum of digits in the numerator of the 100th convergent of the continued fraction for e.
import Euler

convergent n = go $ take n e_cf
  where
    go [a]    = a
    go (a:as) = a + recip (go as)
    e_cf      = 2 : concatMap (\k -> [1, 2*k, 1]) [1..]

main = print $ sum $ (\x->x::[Integer]) $ toDigits $ numerator $ convergent 100