This screenshot shows you how to use the
Cellular
resource to build gnomons from scratch. Alternatively,
you can choose the "build gnomons" starter drawing and manipulate
them in the same way.

Here are the perimeters of $G_6$.

Here are the perimeters of $G_6$ rewritten in terms of their
Fibonacci numbers ($F_1 = 1, F_2 = 1, F_3 = 2, F_4 =3$ and so
on).
Can you draw a diagram showing what happens more generally?