204
There's the 1x1s = 64
then there's the 2x2s = 49
the 3x3's = 36
the 4x4s = 25
the 5x5s = 16
the 6x6s = 9
the 7x7s = 4
and the 8x8 itself = 1
And so the pattern is the summation of n^2 with n ranging from 1 to 8.
I'm going to assume there's no border around the whole thing to add yet another 1.
