For  n x n x n  cube


    - the number of cubes that have 3 blue faces is 8   // the corner cubes;


    - the number of cubes having 2 blue faces is 12*(n-2)  // the cubes along 12 edges, without counting the corner cubes;


    - the number of cubes having 1 blue face  is n^3 - (n-2)^3 - 12*(n-2) - 8.



      In the last formula,  n^3 - (n-2)^2  is the number of all small cubes minus the number of interior cubes,

      that comprise the smaller (n-2)*(n-2)*n-2) cube;


      12*(n-2)  is the number of cubes along 12 edges that have two faces painted blue;


      and 8 is the number of corner cubes, having 3 faces painted blue.