第二个六边形数字

第二个六边形数字系列可以表示为

3, 10, 21, 36, 55, 78, 105, 136, 171, 210, 253, …..

第N个学期

给定整数N。任务是找到给定级数的第N个项。
例子：

Input: N = 1 
Output: 3
Input: N = 4 
Output: 36 
 

方法：想法是找到第二个六边形数字的总称。以下是第二个六角形数的通用项的计算：

1st Term = 1 * (2*1 + 1) = 3 
2nd term = 2 * (2*2 + 1) = 10 
3rd term = 3 * (2*3 + 1) = 21 
4th term = 4 * (2*4 + 1) = 36 
. 
. 
. 
Nth term = n * (2*n + 1) 
Therefore, the Nth term of the series is given as 

$n * (2*n + 1)$
 

 

 

下面是上述方法的实现：

C++

// C++ implementation to
// find N-th term
// in the series
#include 
#include 
using namespace std;
 
// Function to find N-th term
// in the series
void findNthTerm(int n)
{
    cout << n * (2 * n + 1) << endl;
}
 
// Driver code
int main()
{
    int N = 4;
    findNthTerm(N);
 
    return 0;
}

Java

// Java implementation to
// find N-th term
// in the series
class GFG{
     
// Function to find N-th term
// in the series
static void findNthTerm(int n)
{
    System.out.print(n * (2 * n + 1));
}
 
// Driver code
public static void main (String[] args)
{
    int N = 4;
    findNthTerm(N);
}
}
 
// This code is contributed by Ritik Bansal

Python3

# Python3 implementation to
# find N-th term
# in the series
 
# Function to find N-th term
# in the series
def findNthTerm(n):
    print(n * (2 * n + 1))
 
# Driver code
N = 4
 
# Function call
findNthTerm(N)
 
# This code is contributed by Vishal Maurya

C#

// C# implementation to
// find N-th term
// in the series
using System;
class GFG{
     
// Function to find N-th term
// in the series
static void findNthTerm(int n)
{
    Console.Write(n * (2 * n + 1));
}
 
// Driver code
public static void Main()
{
    int N = 4;
    findNthTerm(N);
}
}
 
// This code is contributed by Code_Mech

Javascript

 
// Javascript implementation to
// find N-th term
// in the series
 
// Function to find N-th term
// in the series
function findNthTerm(n)
{
    document.write(n * (2 * n + 1));
}
 
// Driver code
N = 4;
findNthTerm(N);
 

输出：
36

参考： OEIS