Combinations of stepwise increasing integers
Ruby, 65 55 bytes

-&gt;n{(0..2**~-n-2).map{|x|w=1;(1..n).map{|d|w+=x[n-d]}}}

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How:
Partial sum of bits (starting with 1) of all numbers up to 2n-1-2
For example: if the number is 111010011 it becomes:
  1 1 1 0 1 0 0 1 1
  | | |   |     | |
  v v v   v     v v
 +1+1+1  +1    +1+1
  -----------------
1 2 3 4 4 5 5 5 6 7
|
Initialized to 1