def series_sum(n):
if n==0:
return 0
else:
return 1.0/(n*(n+1.0))+series_sum(n-1.0)
print(series_sum(10))
print(series_sum(100))
ZGVmIHNlcmllc19zdW0obik6CglpZiBuPT0wOgoJCXJldHVybiAwCgllbHNlOgoJCXJldHVybiAxLjAvKG4qKG4rMS4wKSkrc2VyaWVzX3N1bShuLTEuMCkKCQkKcHJpbnQoc2VyaWVzX3N1bSgxMCkpCnByaW50KHNlcmllc19zdW0oMTAwKSkKCQo=