求数列3,32,323,3232,32323,323232,.的前n项和.

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求数列3,32,323,3232,32323,323232,.的前n项和.
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求数列3,32,323,3232,32323,323232,.的前n项和.
求数列3,32,323,3232,32323,323232,.的前n项和.

求数列3,32,323,3232,32323,323232,.的前n项和.
通项公式为:
an=32×[1-100^(n/2)]÷(1-100)(n为偶数)
an={23-3.2×100^[(n+1)/2]}÷(1-100)(n为奇数)

有时间再回答你哦

n=1,Sn=3
n=2,Sn=35
n=3,Sn=358
n=4,Sn=3580
n=5,Sn=35803
n=6,Sn=358035
n=7,Sn=3580358
........规律很容易看出来,但是,不好写出通式

让我想想!