1+3+5+.+(2n-5)+(2n-3)+(2n-1)+(2n+1)+(2n+3)
2个回答
1+3+5+.+(2n-5)+(2n-3)+(2n-1)+(2n+1)+(2n+3)
= [1+(2n+3)](n+2) / 2
= (n+2)^2
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