For modeling purposes in need all posible combination to split 8-512 points
in half (50% training, 50% testing). So for instance 10 points, how many
times can I make unique combinations of 5 by 5. The result file should have
in the fist column the number of the combination, and in the second the
order e.g.

1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
2 10
2 1
2 2
2 3
2 4
2 5
2 6
2 7
2 8
2 9
3
..
etc.

Any help is appreciated, regards,

Niels