Mathematics induction (exponential divisible by 2304) $7^{2n} -48n - 1$ is divisible by 2304 for all $n \in N$
so I did, P(n) : $7^{2n}-48n-1=2304k$ (k meaning there is an integer which will depend on n)
Prove base case $P(1): 7^2 - 48(1)-1 = 0$, proving that $k=0$ in the meaning of 'divides' 
$n=k+1$
$7^{2(k+1)}-48(k+1)-1 = 2304l$ (l being for some integer)
I don't know how to proceed any further. could someone show me whats next?
thanks alot

$$7^{2n} -48n - 1|2304$$
$$7^{2n+2} -48(n+1) - 1=49\cdot7^{2n}-48n-49$$
$$=49(7^{2n} -48n - 1)+49\cdot48n-48n$$
$$=49(7^{2n} -48n - 1)+48\cdot48n$$
$$=49(7^{2n} -48n - 1)+2304n$$
