求数列{an}{bn}满足a1=1,a2=r,r>0,bn=ana(n+1)且{bn}是公比为q的等比,设Cn=a (2n-1)+a2n(1)求{an}通项(2)设dn=lgC(n+1)/lgCn,求{dn}最大项与最小项的值r=2的19.2次方-1,q=1/2

已知数列an满足an=31-6n,数列bn满足bn=(a1+a2+...+an)/n,求数列bn的前20项之和. 数列an满足a1+a2+a3+...+an=n^2,若bn=1/an(an+1),求bn的和sn 已知数列{an} {bn} {cn}分别满足a1+a2+…+an=3n^2,bn=a2+a4+…+a2n,cn=a1+a3+…+a2n-1分别求数列{bn} {cn}的通项公式 已知正项数列｛an｝｛bn｝满足,对任意正整数n,都有an,bn,an+1成等差数列,bn,an+1,bn+1成等比数列且a1=10,a2=15求证：数列(根号Bn)是等差数列求数列{an},{bn}通项公式设Sn=1/(a1)+1/(a2)+1/(a3)+.1/(an)如果对任 已知数列{an}满足:a1+a2+a3+…+an=n-an 求证{an-1}为等比数列 令bn=(2-n)(an-1)求数列的最大项已知数列{an}满足:a1+a2+a3+…+an=n-an求证{an-1}为等比数列令bn=(2-n)(an-1)求数列的最大项 数列{An}满足a1=1/2,a1+a2+..+an=n方an,求an 数列{An}{Bn}满足下列条件：A1=0,A2=1,An+2=An+An+1/2,Bn=An+1-An1.求证{Bn}是等比数列 2.求{Bn}的通项公式 已知公差不为0的等差数列｛an｝满足a2=3,a1,a3,a7成等比数列 (1)求an的通项公式已知公差不为0的等差数列｛an｝满足a2=3,a1,a3,a7成等比数列(1)求an的通项公式数列{bn}满足bn=an/an+1+an+1/an,求数列bn前n 求做一题数列题.……已知在等差数列｛an｝中,｜a2-a5｜=6,a1+a2+a3=12.(1)求数列｛an｝的通项公式.(2)若数列｛an｝是递增数列,数列｛bn｝满足3b(n+1)=bn,且b2=1/9,求数列｛bn｝通项公式及数列｛an．bn 设数列｛an}满足a1+3a2+3^2a3+...+3^n-1an=n/3,求（1）数列{an}的通项公式（2）设bn=n/an求数列bn的前n项 设数列{an}{bn}满足a1=b1=6 a2=b2=4 a3=b3=3若{an+1 - an}为等差数列.{bn+1 -bn}为等比数列.分别求{an}{bn}的通项公式. 已知数列an满足a1+2a2+2^2a3+...+2^n-1an=n/2(1).求数列an的通项公式.（2）设bn=(2n-1)an,求数列bn的...已知数列an满足a1+2a2+2^2a3+...+2^n-1an=n/2(1).求数列an的通项公式.（2）设bn=(2n-1)an,求数列bn的前n项和sn 设数列{an},{bn}满足a1=1/2,2na(n+1)=(n+1)an,且{bn}=ln(1+an)+1/2an^2,求a2,a3,a4,并求数列an的通项公式 两个数列{an}和{bn}满足bn=a1+2a2+...+nan/1+2+...+n,求证：若{bn}为等差数列,则数列{an}也是等差数列?能看懂的 数列{an}{bn}满足bn=a1+2a2+3a3+…+nan/(1+2+3+…+n),若数列{an}为等差数列,求证；{bn}为等差数列. 已知正项数列{an},{bn}满足：对任何正整数n,都有an,bn,a(n+1）成等差数列,bn,a(n+1),b(n+1)成等比数列,且a1=10,a2=15求证：数列(根号Bn)是等差数列求数列{an},{bn}通用公式设Sn=1/(a1)+1/(a2)+1/(a3)+.1/(an)如果 已知数列{an}{bn}满足a1=1,a2=3,b(n+1)/bn=2,bn=a(n+1)-an,(n∈正整数),求数列an的通项公式 若数列an满足an=4n-1 又有数列bn满足bk=1/k（a1+a2+……+ak）求数列{bn}得前n项和Sn