在数列{an}中,已知a1=5/6,a2=19/36,且数列log2(a2-a1/3),log2(a3-a2/3),……

log2(an+1-an/3)-log2(an-an-1/3)=1
log2[(a(n+1)-an/3)/(an-a(n-1)/3)]=log2 (2)
(a(n+1)-an/3)/(an-a(n-1)/3)=2
(an-a(n-1)/3)/(a(n-1)-a(n-2)/3)=2
.
(a3-a2/3)/(a2-a1/3)=2
所有式子相乘 (a(n+1)-an/3)/(a2-a1/3)=2^(n-1)
两边分别套上log
化简 就行了.