设数列An的前n项和Sn=2an-2的n次方,求A1,A4

S(n)=2a(n)-2^n当n=1时,S(1)=a(1)=2a(1)-2^1得 a(1)=2；n=2时,S(2)=a(1)+a(2)=2a(2)-2²解得a(2)=a(1)+2²=2+4=6；n=3时,S(3)=a(1)+a(2)+a(3)=2a(3)-2³解得a(3)=a(1)+a(2)+2³=2+6+8=16；n=4时,S(4...