各项为正数的数列{an}的前n项和为Sn,且满足:Sn=(1/4)(an)^2+(1/2)an+1/4
各项为正数的数列{an}的前n项和为Sn,且满足:Sn=(1/4)(an)^2+(1/2)an+1/4
日期:2011-06-25 13:59:04 人气:1
a(n)=2n-1
f(2n-1)=a(2n-1)=2(2n-1)-1=4n-3
f[2^k(2n-1)]=f(2n-1)=4n-3
c(1)=f(2+4)=f(3)=f(2*2-1)=4*2-3=5,
c(2)=f(4+4)=f(1)=f(2*1-1)=4*1-3=1,
n>2时,
c(n)=f[2^n+4]=f[2^(n-2)+1]=f{2*[2^(n-3)+1]-1}=4[2^(n-3)+1]-3=1+2^(n-1)
t(1)=c(1)=5
t(2)=c(1)+c(2)=6