return [ [ 2, 3, 4, 5 ], [ 1, 6, 7, 8 ], [ 1, 8, 9, 10 ], [ 1, 10, 11, 12 ], 
  [ 1, 12, 13, 6 ], [ 2, 5, 14, 15 ], [ 2, 15, 16, 17 ], [ 2, 17, 18, 3 ], 
  [ 3, 18, 19, 20 ], [ 3, 20, 11, 4 ], [ 4, 10, 21, 22 ], [ 4, 22, 13, 5 ], 
  [ 5, 12, 23, 14 ], [ 6, 13, 24, 25 ], [ 6, 25, 16, 7 ], [ 7, 15, 25, 26 ], 
  [ 7, 26, 27, 8 ], [ 8, 27, 28, 9 ], [ 9, 28, 29, 30 ], [ 9, 30, 21, 10 ], 
  [ 11, 20, 30, 31 ], [ 11, 31, 23, 12 ], [ 13, 22, 29, 24 ], 
  [ 14, 23, 32, 33 ], [ 14, 33, 16, 15 ], [ 16, 33, 34, 17 ], 
  [ 17, 34, 28, 18 ], [ 18, 27, 32, 19 ], [ 19, 32, 23, 31 ], 
  [ 19, 31, 21, 20 ], [ 21, 30, 29, 22 ], [ 24, 29, 28, 34 ], 
  [ 24, 34, 26, 25 ], [ 26, 33, 32, 27 ] ];
