(2013•重庆)设数列{an}满足:a1=1,an+1=3an,n∈N+. (
题型:解答题
问题:
(2013•重庆)设数列{an}满足:a1=1,an+1=3an,n∈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项和,且b1=a2,b3=a1+a2+a3,求T20.
(2013•重庆)设数列{an}满足:a1=1,an+1=3an,n∈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项和,且b1=a2,b3=a1+a2+a3,求T20.