∵f(n)=(1-a1)(1-a2)…(1-an),数列{an}的通项公式an= 1 (n?1)2 ,∴f(1)=1?a1=1? 1 4 = 3 4 ,f(2)=(1?a1)(1?a2)=f(1)?(1? 1 9 )= 3 4 ? 8 9 = 2 3 = 4 6 ,f(3)=(1?a1)(1?a2)(1?a3)=f(2)?(1? 1 16 )= 2 3 ? 15 16 = 5 8 .由此猜想,f(n)= n+2 2(n+1) .