(define series_sum
( lambda (n)
(if (= n 0) 0
(+ (/ 1 (* n (+ n 1))) (series_sum(- n 1)))
) ) )
(writeln (series_sum 10))
(writeln (series_sum 100))
(writeln (series_sum 1000))
(writeln (series_sum 10000))
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