已知a>0,數(shù)列{an}是首項(xiàng)及公比均為a等比數(shù)列,前n和為Sn。若bn=anlgan(n屬于N),數(shù)列{bn}的每一項(xiàng)小于它后面一項(xiàng)。（1）求a的取值范圍；（2）若a>1,求lim(Sn/an+2^n) n→∞