Base = (Base of X-1) + 0.21875
Height = ???
(I can't find out how to derive the angle from Height and Base, and so
I can not find how to use some trig function of that angle with only
the Base, to determine the Height after the above simple addition.
Anyone here know all that stuff?)

If you mark a Normal line on the base through the pyramid's top, you
have a right angle triangle with a base of B/2, and the top angle of
theta/2.
so the formula you need is
tan(theta/2) = B/(2H)
theta = 2 arctan(B/2H)
Timothy