求第一个N个居中的八边形数的总和

给定数字N ，任务是找到第一个N个居中的八边形数字的总和。
例子：

Input: N = 3 
Output: 75 
Explanation: 
1, 19 and 55 are the first three centered octadecagonal numbers.
Input: N = 10 
Output: 298 
 

方法：

1. 最初，我们需要创建一个函数，该函数将帮助我们计算第N^个居中的八边形数。
2. 现在，运行一个从1到N的循环，以找到^第i^个居中的八边形数。
3. 将所有上述计算的居中八边形数相加。
4. 最后，显示前N个居中的八边形数字的总和。

下面是上述方法的实现：

C++

// C++ program to find the sum of the
// first N centered octadecagonal numbers
#include
using namespace std;
 
// Function to find the N-th centered
// octadecagonal number
int center_octadecagon_num(int n)
{
 
    // Formula to calculate
    // nth centered octadecagonal
    // number
    return (9 * n * n - 9 * n + 1);
}
 
// Function to find the sum of the first
// N centered octadecagonal numbers
int sum_center_octadecagon_num(int n)
{
 
    // Variable to store
    // the sum
    int summ = 0;
 
    // Iterating through the range
    // 1 to N
    for(int i = 1; i < n + 1; i++)
    {
        summ += center_octadecagon_num(i);
    }
    return summ;
}
 
// Driver Code
int main()
{
    int n = 3;
 
    cout << (sum_center_octadecagon_num(n));
    return 0;
}
 
// This code is contributed by Rajput-Ji

Java

// Java program to find the sum of the 
// first N centered octadecagonal numbers
class GFG {
     
// Function to find the N-th centered
// octadecagonal number
static int center_octadecagon_num(int n)
{
 
    // Formula to calculate
    // nth centered octadecagonal
    // number
    return (9 * n * n - 9 * n + 1);
}
 
// Function to find the sum of the first
// N centered octadecagonal numbers
static int sum_center_octadecagon_num(int n)
{
 
    // Variable to store
    // the sum
    int summ = 0;
 
    // Iterating through the range
    // 1 to N
    for(int i = 1; i < n + 1; i++)
    {
       summ += center_octadecagon_num(i);
    }
    return summ;
}
 
// Driver Code
public static void main(String[] args)
{
    int n = 3;
 
    System.out.println(sum_center_octadecagon_num(n));
}
}
 
// This code is contributed by sapnasingh4991

Python3

# Python3 program to find the sum of
# the first N Centered Octadecagonal
# numbers
 
# Function to find the N-th
# Centered octadecagonal
# number
def center_octadecagon_num(n):
 
    # Formula to calculate 
    # nth centered octadecagonal
    # number
    return (9 * n * n - 9 * n + 1)
     
   
# Function to find the sum of
# the first N Centered
# octadecagonal numbers
def sum_center_octadecagon_num(n) :
     
    # Variable to store
    # the sum
    summ = 0
     
    # Iterating through the range
    # 1 to N
    for i in range(1, n + 1):
 
        summ += center_octadecagon_num(i)
     
    return summ
   
# Driver code
if __name__ == '__main__' :
           
    n = 3
     
    print(sum_center_octadecagon_num(n))

C#

// C# program to find the sum of the
// first N centered octadecagonal numbers
using System;
 
class GFG {
     
// Function to find the N-th centered
// octadecagonal number
static int center_octadecagon_num(int n)
{
 
    // Formula to calculate
    // nth centered octadecagonal
    // number
    return (9 * n * n - 9 * n + 1);
}
 
// Function to find the sum of the first
// N centered octadecagonal numbers
static int sum_center_octadecagon_num(int n)
{
 
    // Variable to store
    // the sum
    int summ = 0;
 
    // Iterating through the range
    // 1 to N
    for(int i = 1; i < n + 1; i++)
    {
        summ += center_octadecagon_num(i);
    }
    return summ;
}
 
// Driver Code
public static void Main(String[] args)
{
    int n = 3;
 
    Console.WriteLine(sum_center_octadecagon_num(n));
}
}
 
// This code is contributed by sapnasingh4991

Javascript

    // Javascript program to find the sum of the 
    // first N centered octadecagonal numbers
     
    // Function to find the N-th centered
    // octadecagonal number
    function center_octadecagon_num(n)
    {
 
        // Formula to calculate
        // nth centered octadecagonal
        // number
        return (9 * n * n - 9 * n + 1);
    }
 
    // Function to find the sum of the first
    // N centered octadecagonal numbers
    function sum_center_octadecagon_num(n)
    {
 
        // Variable to store
        // the sum
        let summ = 0;
 
        // Iterating through the range
        // 1 to N
        for(let i = 1; i < n + 1; i++)
        {
            summ += center_octadecagon_num(i);
        }
        return summ;
    }
     
    let n = 3;
    document.write(sum_center_octadecagon_num(n));
 
// This code is contributed by divyeshrabadiya07.

输出：

75

时间复杂度： O(N)。