return [ rec(
      invers := ( 1, 3)( 2,10)( 4,15)( 5,13)( 6,12)( 7,11)( 8,17)( 9,16)(14,20)(18,19),
      nbP := 20,
      next := ( 1, 2)( 3, 4, 5, 6)( 7, 8, 9,10)(11,12,13,14)(15,16,17,18)(19,20) ), rec(
      invers := ( 1, 3)( 2, 8)( 4,12)( 5,17)( 6,10)( 7, 9)(11,13)(14,20)(15,19)(16,18),
      nbP := 20,
      next := ( 1, 2)( 3, 4, 5, 6)( 7, 8)( 9,10,11,12)(13,14,15,16)(17,18,19,20) ), rec(
      invers := ( 1, 3)( 2, 4)( 5,10)( 6, 7)( 8,11)( 9,12)(13,18)(14,15)(16,19)(17,20),
      nbP := 20,
      next := ( 1, 2)( 3, 4, 5, 6)( 7, 8, 9,10)(11,12,13,14)(15,16,17,18)(19,20) ) ];
