[seqfan] Seq triangles that are unimodular

[Peter Lawrence]

Pascal’s triangle as a matrix turns out to be unimodular (inverse has all integer entries)
Stirling numbers of first kind as matrix and of second kind are inverses of each other
Fibonomal triangle as matrix is unimodular,  A010048, and A103910
Gaussian Binomial Triangles turn out to be unimodular, e.g. A022166 and A135950

Is there a theory of triangular unimodular matricies ?

For a given rank they form a group under multiplication, is there a finite set
of generators (it would seem not) ?, or a simple infinite set ?

Any info or references would be appreciated

Thanks,
Peter A. Lawrence.