数列{an}中,a1=2/3,an+1=an/(1+3an)(n∈N)(1)计算a2,a3,a4(2)猜测an并用数学归纳法证明
(3)设Sn=1/a1+1/a2+...+1/an,求lim(n²/Sn)n趋于无穷大