If $$4^n+15n+P$$ is divisible by 9 for all $$n\in N$$, then the least negative integral value of P is

The total number of terms in the expansion of $${(x + y)^{100}} + {(x - y)^{100}}$$ is

The coefficient of $${x^{20}}$$ in the expansion of $${(1 + 3x + 3{x^2} + {x^3})^{20}}$$ is

In the expansion of $${(1 - 3x + 3{x^2} - {x^3})^{2n}}$$, the middle term is