I'm pretty sure that the numbers are all divisible by 11, and therefore composite (since they are all greater than 11). I'm not sure how to prove divisibility, though.
--Kevin C.
This is not true if n is a multiple of 5, because and therefore .
On the other hand, if n is not a multiple of 5 then and so has an inverse (mod 11). Therefore , so the result is true in that case.
But I don't see how to prove that is composite when n is a multiple of 5.