Problem 43966. Matrix to 3-Column Matrix

Consider a matrix A such as

A = [1 2 3 3 4 5 6;
     2 3 4 5 6 7 8];

Can you convert this matrix to a three-column matrix like this:

M=[1 2 3;
   2 3 3;
   3 3 4;
   3 4 5;
   4 5 6;
   2 3 4;
   3 4 5;
   4 5 6;
   5 6 7;
   6 7 8]

hint: please look at Problem 43964