a) How many elements does the set $\{\varnothing, \{\varnothing,\{\varnothing\}\}, \{\{\varnothing\}\}, \{\{\varnothing\},\varnothing,\varnothing\}\}$ have?

b) What is the power of the set of $A :=\{\varnothing, \{\varnothing\}\}$.

For part b) I was thinking that it has $2^2-1$ elements since $\varnothing$ is itself an element.