euler/Problem065.hs

11 lines
343 B
Haskell

-- 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