内容正文:
扫描全能王 创建
扫描全能王 创建
扫描全能王 创建
扫描全能王 创建
扫描全能王 创建
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Sn - 1 =(n -1)an - 1 -(n -1)2 +(n - 1)(n≥2). ② 1 <EEEEEEEEE
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an = Sn - Sn - 1 = n
2 -(n - 1)2 = 2n - 1(n≥2). 4 <EEEEEEEEEEE
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>?@③,AB Sn槡+ 1 = S槡n + 1,CD Sn槡+ 1 - S槡n = 1. 1 <EEEEEEEE
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{ S槡n}HD 1 BIJK3J!L. M S槡1 = a槡1 = 1, 2 <EEEEEEEE
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