給你看個(gè)例子
數(shù)列{an},a1=1,a（n+1）=an×2n（n整數(shù)）求通項(xiàng)式an...
a1=1
a2=a1*2^1
a3=a2*2^2
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.
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a(n-1)=a(n-2)*2^(n-2)
a(n)=a(n-1)*2^(n-1)
相乘
a(n)=2^1*2^2.*2^(n-1)=2^[n(n-1)/2]