17在序列中,因为以17为中心的9角数是1225,这也是第35个正方形。
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n|=3*a(n)-2|=3*a(n)-1|3*a(n)
--+------------------+-------------------+-------------------
1 | 1^2 = 1 | 1^2*2 = 2 | 1*3 = 3
2 | 7^2 = 49 | 5^2*2 = 50 | 17*3 = 51
3 | 41^2 = 1681 | 29^2*2 = 1682 | 561*3 = 1683
4 | 239^2 = 57121 | 169^2*2 = 57122 | 19041*3 = 57123
5 | 1393^2 = 1940449 | 985^2*2 = 1940450 | 646817*3 = 1940451
(结束)
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