If the general term formula of sequence {an} is an = ncosn π 2, and the sum of the first n terms is Sn, then s2012 is equal to () A. 1006B. 2012C. 503D. 0

If the general term formula of sequence {an} is an = ncosn π 2, and the sum of the first n terms is Sn, then s2012 is equal to () A. 1006B. 2012C. 503D. 0

∵ an = ncosn π 2, and ∵ f (n) = Cosn π 2 is a periodic function with T = 2 π 2 π 2 = 4 as the period, ∵ a1 + A2 + a3 + A4 = (0-2 + 0 + 4) = 2, A5 + A6 + A7 + A8 = (0-6 + 0 + 8) = 2 a2009+a2010+a2011+a2012=(0-2010+0+2012)=2,S2012=a1+a2+a3+a4+… +a2012=(0-...