设数列an=n^2+λn,a1

设数列an=n^2+λn,a1 设数列{an}中,a1=2,an+1=an+n+1,则通项an=? 设数列{an}中,若an+1 =an+ an+2 (n∈N*),则称数列{an}为“凸数列” .设数列{an}为“凸数列”求第二问证明设数列{an}中,若an+1 =an+ an+2 (n∈N*),则称数列{an}为“凸数列” .设数列{an}为“凸数列”,若a1 =1, 设数列｛an｝的通项公式为an=n2+λn(n∈N*)且｛an｝满足a1 设数列｛an｝满足a1+2a2+3a3+.+nan=n(n+1)(n+2)求通项an 设数列{an},a1=2,a（n+1）=an+In·（1+1/n）,求an 设数列﹛an﹜中,a1+4,an=3a(n-1)+2n-1,求通项an 设数列AN满足A1等于1,3(A1+a2+~+AN)=(n+2)an,求通向公式 设数列{an},a1=3,a(n+1)=3an -2 (1)求证:数列{an-1}为等比数列 设数列an满足a1=2,a(n+1)=3an+2^(n-1),求an2,设数列an满足a1=2,a(n+1)=3an+2n,求an 设数列{an}满足a1+a2/2+a3/3+.+an/n=n^2-2n-2,求数列{an}的通项公式 数列｛an｝,中,a1=1/3,设Sn为数列｛an｝的前n项和,Sn=n（2n-1）an 求Sn 已知数列{an}满足a1=-1,an=[(3n+3)an+4n+6]/n,bn=3^(n-1)/an+2.求数列an的通向公式.设数列bn是的前n项和已知数列{an}满足a1=-1,an=[(3n+3)an+4n+6]/n,bn=3^(n-1)/an+2.(1)求数列an的通向公式.(2)设数列bn是的前n项和为sn, 设数列｛an}满足a1+2a2+3a3+……+nan=2^n(n∈N*) 求数列｛an}的通项公式 设bn=n^2*an,求数列bn的前n项和 设数列An的前n项和Sn=2an-2的n次方,求A1,A4 a1=1,a(n+1)=(1+1/n)an+n+1/2^n,设bn＝an/n求数列bn的通项公式 设数列｛an｝中,a1=1且(2n+1)an=(2n-3)a(n-1),(n大于等于2）,求{an},sn 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