xs = 30-ra, a számok:
1, 2, 3, 5, 7, 8, 9, 10, 15
Az eredmény:
[[1,2,3,5,9,10],[1,2,3,7,8,9],[1,2,3,9,15],[1,2,5,7,15],
[1,2,8,9,10],[1,3,7,9,10],[1,5,7,8,9],[1,5,9,15],[2,3,7,8,10],
[2,3,10,15],[2,5,8,15],[3,5,7,15],[3,8,9,10],[5,7,8,10],[5,10,15],[7,8,15]]