已知数列{an}满足an+1^2+2^2+.n^2,则3/a1+5/a2+7/a3.+21/a10=

已知数列{an}满足a1*a2*a3···a(n-1)*an=n^2,则a10-a4= 已知数列{an}满足a1+a2+a3+...+an=n^2+2n.(1)求a1,a2,a3,a4 已知数列{an}满足a1+2a2+3a3+…+nan=n(n+1)(n+2),则a1+a2+a3+…+an=多少? 已知数列{an}满足a1=1,an=a1+2a2+3a3.+(n-1)an-1 (n>=2),则{an}的通项是什么 已知数列{an}满足a1=1;an=a1+2a2+3a3+...+(n-1)a(n-1); 已知数列an满足：a1+a2+a3+...+an=n-an,(n=1,2,3,...)第一问：求a1,a2,a3的值.第 已知各项均为正数的数列{an}中满足,a1=a3,a2=1,an+2=1/1+an则a9+a10=多少? 已知数列{an}满足a1=1,an=a1+1/2a2+1/3a3+...+1/n-1an-1(n>1)求数列{an}的通 设an=1+2^2+3^2+.+n^2,则数列3/a1+5/a2+7/a3+……+21/a10=? 数列{an}满足：1/a1+2/a2+3/a3+…+n/an=2n 数列an满足a1+2a2+3a3+...+nan=(n+1)(n+2) 求通项an 已知数列(an)满足a1+2a2+3a3+...+nan=n(n+1)(n+2)求an