If $a, b$ and $n$ are natural numbers,then $a^{2n-1} + b^{2n-1}$ is divisible by

For all positive integers $n$,if $3(5^{2n+1}) + 2^{3n+1}$ is divisible by $k$,then the number of prime numbers less than or equal to $k$ is:

The numbers $a_n = 6^n - 5n$ for $n = 1, 2, 3, \ldots$ when divided by $25$ leave the remainder:

The least remainder when $17^{30}$ is divided by $5$ is

If $2(4^{2n+1}) + 3^{3n+1}$ is divisible by $k$,where $k > 1$,for all $n \in N$,then the value of $k$ is:

If $(11)^{27} + (21)^{27}$ is divided by $16$,the remainder is: