已知数列{an}满足a1=1 ,a3=3,且对任意m,n∈N﹢都有am-1+a2n-1=2am+n-1求a2,a4.证明{an}是等差数列,并求通项公式an.,都有a2m-1+a2n-1=2am+n-1

已知数列an'满足a1=1/2,a1+a2+a3+...+an=n^2an,求通项公式 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)an-1 (n≥2)求an=? 已知数列｛an｝的前n项和为Sn 1若数列｛an｝是等比数列,满足2a1+a3=3a2.a3+2是a已知数列｛an｝的前n项和为Sn1若数列｛an｝是等比数列,满足2a1+a3=3a2.a3+2是a2.a4的等差中项,求数列｛an｝的通向公式 已知数列,an满足a1=1,a3+a7=18,且an-1+an+1=2an 已知数列{an}满足a1=1 Sn=n² 则a3的值为 已知数列an满足a1=1,a3+a7=18 已知数列{an}满足：a1=1,an=a1+2a2+3a3+``````+(n-1)a(n-1)(n大于等于2）,则通项公式an是什么? 已知数列an满足a1=1,an=a1+2a2+3a3+4a4+.(n-1)a(n-1),求通项an 已知数列{an}满足a1＝1,an=a1＋1/2a2＋1/3a3+…＋1/(n－1)an 几个数列问题.已知数列{an} a1=1,an+1=an/(1+n^2*an) 求an 已知数列{an} 满足a1=1 a1*a2*a3.*an=n^2 求an (1)数列{an}中,a1=1,a2=-3,a(n+1)=an+a(n+2),则a2005=____(2)已知数列｛an｝满足a1=1,a1×a2×a3…an=n^2,求an. 已知数列{an}满足2a1+2^2a2+2^3a3+...+2^nan=4^n-1,则{an}的通项公式2a1+2^2a2+2^3a3就是2a1+4a2+8a3... 已知数列{an}满足a1=1;an=a1+2a2+3a3+...+(n-1)a(n-1)（n≥2);求通项公式 已知数列{an}满足：a1+a2+a3+.+an=n^2,求数列{an}的通项an. 已知等差数列｛an｝满足a3+a6=-1/3,a1*a8=-4/3且a1＞a8求数列｛an}通项公式谢谢了, 已知数列{an}满足a1+2a2+3a3+...+nan=n(n+1)(2n+1),则该数列an=?