因为Bn=A(2n+1)-A(2n-1)
所以B(n+1)-Bn=A(2n+3)+A(2n-1)
令m=n+2
则B(n+1)-Bn=A(2m-1)+A(2n-1)
化简得A(2n+3)+A(2n-1)=2A(2n+1)=8
A(2n+3)-A(2n+1)=A(2n+1)-A(2n-1)+8
B(n+1)=Bn+8
所以B为等差数列
因为Bn=A(2n+1)-A(2n-1)
所以B(n+1)-Bn=A(2n+3)+A(2n-1)
令m=n+2
则B(n+1)-Bn=A(2m-1)+A(2n-1)
化简得A(2n+3)+A(2n-1)=2A(2n+1)=8
A(2n+3)-A(2n+1)=A(2n+1)-A(2n-1)+8
B(n+1)=Bn+8
所以B为等差数列