Here's a shot at it for you. I know you specified D3, E3, etc. but bear with me. You can make a modification for your use.
Column A: Start Number
Column B: End Number
Column C: Result
A3: 2
B3: 10
C3: =D3&E3&F3 (&G3, etc.... results in: 3,4,...8,9)
D3: =A3+1 (I'll assume there's at least one number in between)
E3: =IF(($A3+COLUMN()-3)<($B3),IF(($A3+COLUMN()-3)>($A3+1),"," &($A3+COLUMN()-3),""),"")
F3: IF(($A3+COLUMN()-3)<($B3),IF(($A3+COLUMN()-3)>($A3+1),"," &($A3+COLUMN()-3),""),"")
G3: (etc. It's the exact same formula)
This large formula relies on the fact that the current column - 3 is how much you want to add to A3. For example, cell E3 is in the fifth column. Subtracting three from it and adding to A3 (2) gives us 4 which is the second value you wanted in your list.
If you move columns, then adjust the number "3" in the formula.
(not even gonna ask why you're needing this...

)
-Rob