当k>=2 时a(2k)=2a(2k-1)=2a(2k+1)/3a(2k+2)=2a(2k+1)所以a(2k)=a(2k+2)/3a(2n)=a4*3^(n-1)=2a3*3^(n-1) ,a(2n-1)=a3*3^(n-1)当k=1时 a1=0,a1=0,a(2),a(3)成等差数列所以a(3)=a(2)=0所以a(2n)=a(2n-1)=0故an=0...