Given that,
7n+1+3n+1
We know that, an+bn is divisible by (a+b) for even natural number n.
Hence, 7n+1+3n+1 is divisible by (7+3)=10 for even natural number n.
For all natural numbers n, 23n−7n−1 is divisible by
For all natural numbers n, 102n−1+1 is divisible by
For every natural number n, n(n2−1) is divisible by