<><><>, 3 bytes
Also see this post, but <><><> needs the explicit print and termination so we can't go under 3 bytes.
=n; But this is a pretty boring solution. There are two 5 byte solutions
1nnn; and
1++n; that are only slightly more interesting. For input a and b, the first one works by printing 1ba and the second by printing a+b+1.
Here is a TIO test bench where bytes 2-5 should be replaced by the first 4 bytes of a solution.