If $$49^n+16n+P$$ is divisible by 64 for all $$n\in N$$, then the least negative integral value of P is

$${2^{3n}} - 7n - 1$$ is divisible by

Number of terms in the binomial expansion of $$(x+a)^{53}+(x-a)^{53}$$ is

The coefficient of $$x^{10}$$ in the expansion of $$1+(1+x)+...+(1+x)^{20}$$ is