I would like to efficiently generate a unique list of combinations of numbers based on a starting list of numbers.
example start list = [1,2,3,4,5] but the algorithm should work for [1,2,3...n]
result =
[1],[2],[3],[4],[5]
[1,2],[1,3],[1,4],[1,5]
[1,2,3],[1,2,4],[1,2,5]
[1,3,4],[1,3,5],[1,4,5]
[2,3],[2,4],[2,5]
[2,3,4],[2,3,5]
[3,4],[3,5]
[3,4,5]
[4,5]
Note. I don't want duplicate combinations, although I could live with them, eg in the above example I don't really need the combination [1,3,2] because it already present as [1,2,3]
