There are square numbers, we can imagine these as a square of dots
Squ(n) $= n^2$
There are triangle numbers with we can imagine as a triangle of dots
tri(n) $=\frac{n(n+1)}{2}$
There are pentagonal numbers we can imgaine these as a pentagon of dots
Pent(n) $= \frac{3n^2 - n}{2}$
Square numbers have a three dimensional counterpart that are cubic numbers, so do triangular numbers.
The question is what is the nth 3D pentagonal number?
In On Regular Polytope Numbers, Kim extends the notion of figurate numbers to 3-D solids. The Dodecahedral numbers seem to be what you describe, and are counted by $$ D_n=\frac{n(3n-1)(3n-2)}{2} $$