return [ rec(
      invers := ( 1, 4)( 2,11)( 3, 7)( 5,10)( 6,14)( 8,13)( 9,15)(12,16),
      nbP := 16,
      next := ( 1, 2, 3)( 4, 5, 6)( 7, 8, 9,10)(11,12,13)(14,15,16) ) ];
