[C++] Nested Radical Constant

做高數助教被天煞的大一學生坑了，發現是個未解問題，沒有解析解。。

用C搞了下，就是這樣。。。

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No closed-form expression is known for this constant (Finch 2003, p.?8; S.?Plouffe, pers. comm., Aug.?29, 2008).

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/*****************************************
*@: Nested Radical Constant 嵌套根式常數
*@: http://mathworld.wolfram.com/NestedRadicalConstant.html
*****************************************/
#include "stdafx.h"
#include <stdio.h>
#include <math.h>
void main(void){int N = 10;int idx = 0;double an = 0;double temp = 0;an = sqrt(double(N));for(idx =(N-1);idx >= 1; idx--){temp = idx + an;an = sqrt(temp);	}printf("N=%d,an=%f \n",N,an);getchar();
}