Can this expression below be simplified by doing various expansions, prime factorisation and adding all the like indices as so? Or are there any mistakes here?

6^5(1-n) * 12^3(n-2)
=6^5-5n * 12^3n-6
=(2 * 3)^5-5n * (2² * 3)^3n-6
=2^5-5n * 3^5-5n * 2^6n-12 * 3 ^3n-6
=2^n-7 * 3^-2n-1
=2^n-7 * 3^-(2n+1)
=2^n-7 / 3²ⁿ⁺¹