四八角形数

给定数N ，任务是找到^第N^个四对八边形数。

A Tetracontaoctagon number is a class of figurate numbers. It has a 48-sided polygon called Tetracontaoctagon. The N-th Tetracontaoctagonal number count’s the 48 number of dots and all other dots are surrounding with a common sharing corner and make a pattern. The first few Tetracontaoctagonol numbers are 1, 48, 141, 280, 465, 696, … 
 

例子：

Input: N = 2 
Output: 48 
Explanation: 
The second Tetracontaoctagonol number is 48. 
Input: N = 3 
Output: 141 
 

方法：第N个四八角形数由下式给出：

• 侧多边形的第N个项= $\frac{((s-2)n^2 - (s-4)n)}{2}$
• 因此48个面的多边形的第N个项是

$Tn =\frac{((48-2)n^2 - (48-4)n)}{2} =\frac{(46^2 - 44)}{2}$

下面是上述方法的实现：

C++

// C++ implementation for
// above approach
#include 
using namespace std;
 
// Function to find the
// nth Tetracontaoctagonal Number
int TetracontaoctagonalNum(int n)
{
    return (46 * n * n - 44 * n) / 2;
}
 
// Driver Code
int main()
{
    int n = 3;
    cout << TetracontaoctagonalNum(n);
 
    return 0;
}

Java

// Java program for above approach
class GFG{
 
// Function to find the
// nth TetracontaoctagonalNum Number
static int TetracontaoctagonalNum(int n)
{
    return (46 * n * n - 44 * n) / 2;
}
 
// Driver code
public static void main(String[] args)
{
    int n = 3;
    System.out.print(TetracontaoctagonalNum(n));
}
}
 
// This code is contributed by shubham

Python3

# Python3 Cimplementation for
# above approach
 
# Function to find the
# nth Tetracontaoctagonal Number
def TetracontaoctagonalNum(n):
 
    return (46 * n * n - 44 * n) / 2;
 
# Driver Code
n = 3;
print(TetracontaoctagonalNum(n));
 
# This code is contributed by Code_Mech

C#

// C# program for above approach
using System;
class GFG{
 
// Function to find the
// nth TetracontaoctagonalNum Number
static int TetracontaoctagonalNum(int n)
{
    return (46 * n * n - 44 * n) / 2;
}
 
// Driver code
public static void Main()
{
    int n = 3;
    Console.Write(TetracontaoctagonalNum(n));
}
}
 
// This code is contributed by Code_Mech

Javascript

 
// Javascript implementation for
// above approach
 
// Function to find the
// nth Tetracontaoctagonal Number
function TetracontaoctagonalNum(n)
{
    return (46 * n * n - 44 * n) / 2;
}
 
// Driver Code
var n = 3;
document.write(TetracontaoctagonalNum(n));
 
 

输出：

141

参考： https : //en.wikipedia.org/wiki/Tetracontaoctagon