23n−7n−1 s divisible by

Let  P(n)=23n−7n−1⇒P(1)=0,P(2)=49P(1) and P(2) are divisible by 49. Let P(k)=23k−7k−1=49lP(k+1)=23k+3−7k−8=8(49)+7k+1)−7k−8=49(8/)+49k=49λwhere, λ=8I+k which is an integer.