设数列an的前n想和位sn，a1=1,an+1=nsn+1，且a1,2a2,a3+3为等差数列bn的

设数列an前n项和Sn已知a1=a2=1bn=nSn+（n+2）an数列bn公差为d的等差数列n属于N...设数列an前n项和Sn已知a1=a2=1bn=nSn+（n+2）an数列bn公差为d的等差数

设数列{an}和{bn}满足:a1=b1=6,a2=b2=4,a3=b3=3,数列{an+1-an}是等差数列···设数列{an}和{bn}满足:a1=b1=6,a2=b2=4,a3=b3=3,数列{

已知数列{An}的前n项和为Sn,A1=A2=1,bn=nSn+（n+2)An,数列{bn}是公差为d的等差数列,证（A1A2.An)(S1.Sn)已知数列{An}的前n项和为Sn,A1=A2=1,b

设数列{an}和{bn}满足a1=b1=6,a2=b2=4,a3=b3=3,且数列{an+1-an}是等差数列设数列{an}和{bn}满足a1=b1=6,a2=b2=4,a3=b3=3,且数列{a(n

已知数列{an}是等差数列,a1=1,a1+a2+a3=12.令bn=3^an,求数列{bn}的前n项和sn.已知数列{an}是等差数列,a1=1,a1+a2+a3=12.令bn=3^an,求数列{b

设数列An的前n项和为Sn,满足2Sn=An+1-2^n+1+1,且A1.A2+5.A3成等差数列求数列的设数列An的前n项和为Sn,满足2Sn=An+1-2^n+1+1,且A1.A2+5.A3成等差

设数列an是各项为正数的等比数.列,Sn为数列an前n项和,1.已知S3=7,且a1+1,3a2,a3+6成等差数列,求an同项公式.2.令Bn=lgan,若a1=1,b3=2,求数列（2的n次方bn

设数列an是各项为正数的等比数.列,Sn为数列an前n项和,1.已知S3=7,且a1+1,3a2,a3+6成等差数列,求an同项公式.2.令Bn=lgan,若a1=1,b3=2,求数列（2的n次方bn

设数列an的前n项和为Sn,满足2Sn=an－2∧n+1+1,且a1,a2+5,a3成等差设数列an的前n项和为Sn,满足2Sn=an－2∧n+1+1,且a1,a2+5,a3成等差数列.求a1,an的

已知数列{an}是等差数列,且a1=2,a1+a2+a3=12(1)求数列{an}的通项公式.(2)令bn=3^an,求{bn}的前n项和sn已知数列{an}是等差数列,且a1=2,a1+a2+a3=

递增等差数列an满足a1=1,a1,a2,a3为等比数列.设bn=an+2的an次方,求数列bn的前n向和sn递增等差数列an满足a1=1,a1,a2,a3为等比数列.设bn=an+2的an次方,求数

已知数列﹛an﹜的前n项和为Sn,a1=1,且2nSn+1－2(n+1)Sn=n²+n(n∈N*).（1）求数列{an}的通项公式；（2）设bn=n/2(n+3)Sn,求数列{bn}的前n项

设数列An,Bn满足a1=b1=6,a2=b2=4,a3=b3=3,且数列A(n+1)-An(n属于正整数)是等差数列.设数列An,Bn满足a1=b1=6,a2=b2=4,a3=b3=3,且数列A(n

数列{an}前n项和为Sn=4-1/4^(n-1),数列bn为等差数列,且b1=a1,a2(b2-b1)=a1.设cn=an*bn,求数列cn的前n项和数列{an}前n项和为Sn=4-1/4^(n-1

有关数列的一道题在数列an中a1=-3an=2an-1+2^n+3n大于等于2且为正整数1）求a2a3的值2）设bn=an+3比2^nn属于正整数证明bn为等差数列3）求数列an的前n项和Sn有关数列

设数列{An}满足,A1=1,An+1=3An,n属于N+.（1）求An的通项公式及前n项和Sn(2)已知bn是等差数列,Tn为前n项的和,且b1=a2,b3=a1+a2+a3,求T10设数列{An}

设{an}是公比大于1的等比数列,Sn为数列{an}的前n项和.已知S3=7,且(a1)+3,3(a2),(a3)+4构成等差数列.(1)求数列{an}的等差数列.(2)令bn=1/n(n+1)+a2

在等差数列{an}中,已知a1+a2+a3=9,a2+a4+a6=21,(1)求数列{an}的通项公式(2)设bn=2^n乘an,求数列{bn}的前n项和sn在等差数列{an}中,已知a1+a2+a3

强大的数学题：设数列{An}的前N项和为Sn已知A1=.设数列{An}的前N项和为Sn,已知A1=1,A2=6,A3=11,且(5n-8)Sn+1-(5n+2)Sn=-20n-8(n=1,2,3,4,

已知{an}为等差数列,且a1=2,a1+a2+a3=12.(1)求数列{an}的通项公式（2）令bn=an·3^n,求数列{bn}的前n项和已知{an}为等差数列,且a1=2,a1+a2+a3=12