已知数例{an}满足a1=1,a(n+1)=2an+1求数例{an}前n项和

问题描述:

已知数例{an}满足a1=1,a(n+1)=2an+1求数例{an}前n项和

Sn=[n(A1+An)]/2; Sn=nA1+[n(n-1)d]/2 D=(n-1)/-1 S{an}=3n/2-1