给定一个数N ,任务是找到第N个二十五边形数。
An Icosihenagonal number is class of figurate number. It has 21 – sided polygon called Icosihenagon. The n-th Icosihenagonal number counts the 21 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few Icosihenagonal numbers are 1, 21, 60, 118, 195, 291, 406 …
例子:
Input: N = 2
Output: 21
Explanation:
The second Icosihenagonal number is 21
Input: N = 6
Output: 291
方法:在数学中,第 N个二十五边形数由以下公式给出:
下面是上述方法的实现:
C++
// C++ program to find nth
// Icosihenagonal number
#include
using namespace std;
// Function to find
// Icosihenagonal number
int Icosihenagonal_num(int n)
{
// Formula to calculate nth
// Icosihenagonal number
return (19 * n * n - 17 * n) / 2;
}
// Driver Code
int main()
{
int n = 3;
cout << Icosihenagonal_num(n) << endl;
n = 10;
cout << Icosihenagonal_num(n) << endl;
return 0;
}
Java
// Java program to find nth
// Icosihenagonal number
class GFG{
// Function to find
// Icosihenagonal number
static int Icosihenagonal_num(int n)
{
// Formula to calculate nth
// Icosihenagonal number
return (19 * n * n - 17 * n) / 2;
}
// Driver Code
public static void main(String[] args)
{
int n = 3;
System.out.print(Icosihenagonal_num(n) + "\n");
n = 10;
System.out.print(Icosihenagonal_num(n) + "\n");
}
}
// This code is contributed by Rajput-Ji
Python3
# Python3 program to find nth
# icosihenagonal number
# Function to find
# icosihenagonal number
def Icosihenagonal_num(n):
# Formula to calculate nth
# icosihenagonal number
return (19 * n * n - 17 * n) / 2
# Driver Code
n = 3
print(int(Icosihenagonal_num(n)))
n = 10
print(int(Icosihenagonal_num(n)))
# This code is contributed by divyeshrabadiya07
C#
// C# program to find nth
// Icosihenagonal number
using System;
class GFG{
// Function to find
// Icosihenagonal number
static int Icosihenagonal_num(int n)
{
// Formula to calculate nth
// Icosihenagonal number
return (19 * n * n - 17 * n) / 2;
}
// Driver Code
public static void Main()
{
int n = 3;
Console.Write(Icosihenagonal_num(n) + "\n");
n = 10;
Console.Write(Icosihenagonal_num(n) + "\n");
}
}
// This code is contributed by Code_Mech
Javascript
输出:
60
865
参考: https : //en.wikipedia.org/wiki/Polygonal_number
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