You have to generate a matrix with all possible combinations of n elements taken 2 at a time, without using nchoosek(1:n,2) :
Examples
if n = 3
output =
1 2 1 3 2 3
if n = 5
output =
1 2 1 3 1 4 1 5 2 3 2 4 2 5 3 4 3 5 4 5
Good luck!!
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Solution 272333
so not cool!!