Cardinality of (a,b) Pair Densities in Abstract Predecessor Tree

-- based on same "power-of-2" depths (less lopsided)
-- based on many more, less dense (but still infinite) subsets
-- use the density contribution of every (a,b) pair in 2^a*3^b coefficients

-- in general there are several paths to any 2^a*3^b*n+{c} formula, because e(s|b)_(m-1)t will have all permuations of s-steps and b-steps

-- when sorted the file of formulas of the abstract tree nodes reveals the cardinalities of the sets sharing an (a,b) pair

-- the cardinalities are the elements of the Fibonacci series
-- the situation is easily envisaged using Pascal's triangle