# A question about an asymtotic lower bound for a function

Discussion in 'Math Research' started by Rodolfo Conde, Aug 9, 2011.

1. ### Rodolfo CondeGuest

Hi everyone,

Let n >= 2 be given. Define the function f \colon N \to N (N =
natural numbers) by

f(n) = \sum_{m=2}^n ceiling(n/m)

Question: Is f(n)=\Omega(n^2) ??

I have tried to prove it, but without success, i can't see
exactly which technique i should use. Any suggestions will be greatly
appreciated.

Thanks everyone...

Greetings...

Rodolfo Conde, Aug 9, 2011