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