 | Infinite sequence of exact values of Dirichlet beta-function at odd arguments, starting with @β(1)@.
--
-- >>> import Data.ExactPi
-- >>> approximateValue (betasOdd !! 25) :: Double
-- 0.9999999999999987
-- >>> import Data.Number.Fixed
-- >>> approximateValue (betasOdd !! 25) :: Fixed Prec50
-- 0.99999999999999999999999960726927497384196726751694
betasOdd :: [ExactPi]
betasOdd = zipWith Exact [1, 3 ..] $ zipWith4
                                     (\sgn denom eul twos -> sgn * (eul % (twos * denom)))
                                     (cycle [1, -1])
                                     (skipOdds factorial)
                                     (skipOdds euler)
                                     (iterate (4 *) 4)

-
betasOdd :: [ExactPi]
betasOdd = zipWith Exact [1, 3 ..] $ zipWith4
                                     (\sgn denom eul twos -> sgn * (eul % (twos * denom)))
                                     (cycle [1, -1])
                                     (skipOdds factorial)
                                     (skipOdds euler)
                                     (iterate (4 *) 4)
betasOdd = zipWith Exact [1, 3 ..] $ zipWith4
                                     (\sgn denom eul twos -> sgn * (eul % (twos * denom)))
                                     (cycle [1, -1])
                                     (skipOdds factorial)
                                     (skipOdds euler)
                                     (iterate (4 *) 4)