数列{an}是等差数列,a1=-2,a3=2 求"若bn=2的an次方,求数列{an*bn}的前n项和Sn.

1.已知数列{an}是等差数列,a1=2,a1+a2+a3=12,令bn=3^an,求数列{bn}的前n项和Sn. a1=1.an+1=2an+2^n.bn=an/2^n-1.证明bn是等差数列、求数列的前n项和sn? 数列（an)的前n项和Sn=an的2次方+bn,试证明数列是等差数列,并求a1和d 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,且a1=2,a1+a2+a3=12 令bn=an*3^n,求{bn}的前n项和 已知等差数列an=2n-1,若数列bn=an+q^an,求数列｛bn｝的前n项和Sn,求详解 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 数列{an},a1=1,an=2-2Sn,求an,若bn=n*an,求{bn}的前n项和Tn 已知数列｛an｝为等差数列,且a1=2,a1+a2+a3=12 令bn=3^a n,求数列{bn}的前n项和 数列an中,a1=1,an+1=2an+2的n次方,设bn=an／2∧n-1,证明bn是等差数列,求数列an的前n项和s a1+a2+a3=-6 a1*a2*a3=64 bn=(2n+1)*an 求数列{bn}的前n项和 sn的通向公式 设数列{an}是一等差数列,数列{bn}的前n项和为Sn=2/3（bn-1）,若a2=b1,a3=b2 1.求数列{an