+1 vote

The pyramid can not have four sides symmetrically. with the balls meshed with each other that way.

The 30 solution is based on a non-meshed arrangement which is in total conflict with what is displayed.

The one side you see is identical to the bottom side and has 10 balls. Figure it from there.

If you attempt to build a forth side, the result is nothing near a pyramid and the shape become distorted no matter how you try to do it.

...

base 4*4 = 16

3rd row 3*3 = 9

2nd row 2*2 = 4

nd top row 1

totally 30