Let P_{0}(x)=x^{3}+313 x^{2}-77 x-8. For integers n \geq 1, define P_{n}(x)=P_{n-1}(x-n). What is the coefficient of x in P_{20}(x)?
Let P_{0}(x)=x^{3}+313 x^{2}-77 x-8. For integers n \geq 1, define P_{n}(x)=P_{n-1}(x-n). What is the coefficient of x in P_{20}(x)?