当n是奇数时，Sn=[(n+1)/2][6+(5n+1)]/2+2[1-2^(n-1)/2]/(1-2) =(5n+7)(n+1)/4+2[2^(n-1)/2]-2 当n是偶数时，Sn==(n/2)[6+(5n+1)]/2+2[1-2^(n/2)]/(1-2) =n(5n+7)/4+2[2^(n/2)]-2
答：n=2k-1,k∈N+, S<2k-1>=6+16+……+[5（2k-1)+1]+2+2^2+……+2^（k-1) =k(5k+1)+2^k-2; 同理S<2k...详情>>
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