1.下列数列中,既是递增数列又是无穷数列的是( )
A.1, ,…
B.-1,-2,-3,-4,…
C.-1,-,-,-,…
D.1, ,…,
2.数列1, ,…的一个通项公式an=( )
A. B. C. D.
3.已知数列{an}的前n项和为Sn,若Sn=2an-4(n∈N+),则an=( )
A.2n+1 B.2n
C.2n-1 D.
4.已知数列{an}满足a1+a2+…+an=2a2(n=1,2,3,…),则( )
A.a1<0 B.a1>0
C.a1≠a2 D.a2=0
5.已知数列{an}的前n项和为Sn,a1=2,Sn= an(n∈N+),则S10为( )
A.50 B.55 C.100 D.110
6.已知数列{an}的首项a1=1,其前n项和Sn=n2an(n∈N+),则a9=( )
A. B. C. D.
7.在数列{an}中,a1=1,Sn= an,则an= .
8.数列{an}的前n项和为Sn.若S2=4,an+1=2Sn+1,n∈N+,则S5= .
9.在数列{an}中,a1=0,an+1= ,则S2 019= .
10.数列{an}的通项公式是an=n2+kn+4.
