@goldbiggod, your example creates a vector n, with elements 1, 2 and 3, then you ask for elements larger than zero, which is all of them.
You have still to show us some code, which shows us, that you have put in a effort to solve the challenge. If you just want it to work, you can do this:
library(utils)
combn(1:3, 2)
# [,1] [,2] [,3]
# [1,] 1 1 2
# [2,] 2 3 3
and then if you want
apply(combn(1:3, 2),2,function(x){ return( paste0('(',x[1],',',x[2],')') ) })
# [1] "(1,2)" "(1,3)" "(2,3)"