[0] ->  1 4 6 8 9 ...
[1] ->  1 3 5 6 20 ...
[2] ->  2 3 4 5 6 ...
[3] ->  5 7 8 9 12 ...
[4] ->  3 5 8 11 13...
[5] ->  4 5 7 8 9 ...
[6] ->  1 4 5 7 8 ...
...