an是等差数列,a1=1,S2013/2013-S2009/2009=4,则S2013=() A.2013 B.4024 C.4026 D.4028

an= a1+(n-1)d
S2013/2013 - S2009/2009 =4
(a1+1006d) - (a1+1004d) =4
2d=4
d=2
S2013 = (a1+1006d)2013
=(2013)^2 =4052169没有选项的答案？没有如果a2013 = 2a1+1006d = 2013