Prove by induction that 13^n - 6^(n - 2) is divisible by 7, n subset N.

: n = 1...Step 1

13^1 - 6^(1 - 2) = 13 - 6^-1 = 13 - 0.1666 = 12.833

Can someone help me spot where I've gone wrong on the calcualtion to prove n = 1 yields a number divisible by 7?

Thank you.