数列{an}满足a1=3,a n+1=2an,则a4等于

问题描述:

数列{an}满足a1=3,a n+1=2an,则a4等于

数列为等比数列q=a(n+1)/an=2
an=3*2^(n-1)
a4=3*2^(4-1)=24