Actually, 14 18 bytes
A simple algorithm.
Edit: Fixing a bug for n == 1
;;D╤$0D@H@u*'1@+╪i Ungolfing
Implicit input: n ;; Duplicate n twice. D╤$ Push str(10**(n-1)) 0D@H Push str(10**(n-1))[:-1] @u* Push str * (n+1) '1@+ Append a "1" ╪ Split into chunks of length n i Flatten this list onto the stack Implicit print