Find function that satisfy the relation
Check the definitions (as commonly used in Computer Science, mostly for run time or other resource consumption):

$f(n) = O(g(n))$ if there is a constant $c_1 &gt; 0$ so that for some $N_1$ we have for $n \ge N_1$ that $f(n) \le c_1 g(n)$

$f(n) = \Omega(g(n))$ if there is a constant $c_2 &gt; 0$ so that for some $N_2$ we have for $n \ge N_2$ that $f(n) \ge c_2 g(n)$

$f(n) = \Theta(g(n))$ if both $f(n) = O(g(n))$ and $f(n) = \Omega(g(n))$

$f(n) = o(g(n))$ if $\lim_{n \to \infty} \dfrac{f(n)}{g(n)} = 0$

$f(n) \sim g(n)$ if $\lim_{n \to \infty} \dfrac{f(n)}{g(n)} = 1$

$f(n) = \omega(g(n))$ if $\lim_{n \to \infty} \dfrac{f(n)}{g(n)} = \infty$

You see that $f(n) = \Omega(g(n))$ (one part of $f(n) = \Theta(g(n))$) and $f(n) = o(g(n))$ can't be true simultaneously (check the definition of the limit).