Give an example of a function f $($n$)$ such that:

$$ f $($n$)$ in O$($n$2\mathrm{.}5)$ and f $($n$)$ in $($n$2$ log$2($n$))$ but f $($n$)$ in $\backslash$Theta $($n$2\mathrm{.}5)$ and f $($n$)$ in $\backslash$Theta $($n$2$ log$2($n$)).$