For all n∈N,2⋅42n+1+33n+1 is divisible by
For n=1, we have
2⋅42n+1+33n+1=2×43+34=209 which is divisible by 11
For n=2, we have
2⋅42n+1+33n+1=2×45+37=4235 which is divisible by 11
Similarly, it can be checked that 2.42n+1+33n−1 is divisible by 11 for other values of n