A function that is Big O (1) but not Ω (1)

Question

Can someone help me with the Big O (1) function, but not with Q (1), but vice versa? Some explanation will help a lot.

Answer 1

Big-O signs mean <= and large Omega values> =, so the function, which is O (1) but not Omega (1), is f (n) = 1 / n. For the contrary, f (n) = n works.