一个数列求和题目 错位相减

c(n) =1*1/3+3*(1/3)^2+.+(2n-3)*(1/3)^(n-1)+(2n-1)*(1/3)^n1/3c(n)=1*(1/3)^2+. .+(2n-3)*(1/3)^n+(2n-1)*(1/3)^(n+1)两式相减2/3c(n)=1/3+2[(1/3)^2+.+(1/3)^n]-(2n-1)*(1/3)^(n+1)接下来自己算一...