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

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

The total number of terms in the expansion of $$(x+y)^{60}+(x-y)^{60}$$ is

The coefficient of $$x^{29}$$ in the expansion of $$\left(1-3 x+3 x^2-x^3\right)^{15}$$ is