1 |
2 |
∴2Sn+1+1=4Sn+2,
2Sn+1+1 |
2Sn+1 |
2S1+1=2a1+1=2,
∴數(shù)列{2Sn+1}是以2為首項(xiàng),2為公比的等比數(shù)列,
2Sn+1=2n,
Sn=
2n?1 |
2 |
n≥2時(shí),an=Sn-Sn-1=
2n?1 |
2 |
2n?1?1 |
2 |
n=1時(shí),a1=21-2=
1 |
2 |
∴數(shù)列{an}的通項(xiàng)公式an=2n-2.
故答案為:an=2n-2.
1 |
2 |
1 |
2 |
2Sn+1+1 |
2Sn+1 |
2n?1 |
2 |
2n?1 |
2 |
2n?1?1 |
2 |
1 |
2 |