當(dāng)n≥2時(shí),an=Sn-Sn-1=3n2-2n-[3(n-1)2-2(n-1)]=6n-5,
當(dāng)n=1時(shí),a1=S1=1,符合上式,
所以an=6n-5,
則數(shù)列{an}以6為公差、1為首項(xiàng)的等差數(shù)列;
(2)由(1)得,an=6n-5,
所以bn=
3 |
an?an+1 |
3 |
(6n?5)(6n+1) |
1 |
2 |
1 |
6n?5 |
1 |
6n+1 |
則Tn=
1 |
2 |
1 |
7 |
1 |
7 |
1 |
13 |
1 |
6n?5 |
1 |
6n+1 |
=
1 |
2 |
1 |
6n+1 |
因?yàn)閚∈N*,所以
1 |
6n+1 |
1 |
2 |
1 |
6n+1 |
1 |
2 |
又Tn<
m |
20 |
所以
m |
20 |
1 |
2 |
所以滿足條件的最小正整數(shù)m為:10.