(define series_sum_1
 ( lambda (n)
  (if (= n 0) 0 
    (+ (/ 1.0 (* (+ n 1.0 )(+ n 2.0))) (series_sum_1(- n 1.0)))
  ) ) )
(writeln (series_sum_1 10))
(writeln (series_sum_1 100))
(writeln (series_sum_1 1000))
(writeln (series_sum_1 10000))
(writeln (series_sum_1 100000))
(writeln (series_sum_1 1000000))