已知数列{An}的前n项为Sn,......急急急急急急急
的有关信息介绍如下:X[a]表示X的第a项键伏(1)A[n+1]=S[n+1]-S[n]=(A[n+1] +1)(2A[n+1] -1)/2-(A[n] +1)(2A[n] -1)/2=-A[n]/2 - A[n]^2 + 1/2 A[1 + n] + A[1 + n]^2A[n+1]=-A[n]/2 - A[n]^2 + 1/2 A[n+1] + A[n+1]^2A[n+1]^2-1/2 A[n+1]-(A[n]^2+A[n]/2)=0A[n+1]=-A[n]或A[n]+1/2(2)当A[n+1]=-A[n]则A[n]=(-1)^(n-1) A[1]A[2005]=-A[1]当A[n+1]=A[n]+1/2则A[n]=(n-1)/2+A[1]A[2005]=1003+A[1]可能为A[1]+1003或-A[1](3)当A[n]=(-1)^(n-1) A[1]B[n]=-1/2 (1 - (-1)^n) A[1]当咐亮卖A[n]=(n-1)/2+A[1]B[n]=n A[1]+n(n-1)/4(4)当A[n]=(-1)^(n-1) A[1]B[n]=-1/2 (1 - (-1)^n) A[1]B[n+1]=-1/2 (1 + (-1)^n) A[1]B[n+1]/衡逗B[n]=(1- (-1)^n)/(1 + (-1)^n)发散当A[n]=(n-1)/2+A[1]B[n]=n A[1]+n(n-1)/4B[n+1]=(n+1)A[1]+n(n+1)/4lim[B[n+1] /B[n]]= 1