A:are making
B:is making
C:making
已知数列{an}的前n项和为Sn,a1=2,Sn=n2+n.
(1)求数列{an}的通项公式;
(2)设{1Sn}的前n项和为Tn,求证Tn<1.
毕竞____ 因该____ 咳漱____
告戒____ 坚难____ 已后____