数列{bn}前n项和Sn=(3/2)n^2-(1/2)n,缺常数项,
∴{bn}是等差数列,bn=Sn-S=(3/2)(2n-1)-1/2=3n-2.
∴(an)^3=4^[-(bn+2)]=4^(-3n),
∴an=4^(-n),
∴cn=anbn=(3n-2)*4^(-n)=(3n-2)/4^n.
数列{bn}前n项和Sn=(3/2)n^2-(1/2)n,缺常数项,
∴{bn}是等差数列,bn=Sn-S=(3/2)(2n-1)-1/2=3n-2.
∴(an)^3=4^[-(bn+2)]=4^(-3n),
∴an=4^(-n),
∴cn=anbn=(3n-2)*4^(-n)=(3n-2)/4^n.