Sn/n=3n-2
则Sn=3n^2-2n
n>1时
An=S(n)-S(n-1)
=3n²-2n-[3(n-1)²-2(n-1)]
=3n²-2n-3(n²-2n+1)+2n-2
=-2n+6n-3+2n-2
=6n-5
A1=S1=1
满足上式
所以
An=6n-5
Sn/n=3n-2
则Sn=3n^2-2n
n>1时
An=S(n)-S(n-1)
=3n²-2n-[3(n-1)²-2(n-1)]
=3n²-2n-3(n²-2n+1)+2n-2
=-2n+6n-3+2n-2
=6n-5
A1=S1=1
满足上式
所以
An=6n-5