问题
填空题
数列{1+
|
答案
Sn=(1+
)+(1+1 2
)+…+(1+1 22
)1 2n
=1+1+…+1+(
+1 2
+…+1 22
)1 2n
=n+
[1-(1 2
)n]1 2 1- 1 2
=n+1-1 2n
故答案为：n+1-1 2n-1
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数列{1+
|
Sn=(1+
)+(1+1 2
)+…+(1+1 22
)1 2n
=1+1+…+1+(
+1 2
+…+1 22
)1 2n
=n+
[1-(1 2
)n]1 2 1- 1 2
=n+1-1 2n
故答案为：n+1-1 2n-1