Número octogonal

Se le da un número n, la tarea es encontrar el n ^número octogonal. Además, encuentre la serie Octogonal hasta el n.
Un número octogonal es el número de la figura que representa el octágono. Los números octagonales se pueden formar colocando números triangulares en los cuatro lados de un cuadrado. El número octogonal se calcula usando la fórmula (3n ² – 2n) . 
Ejemplos: 
 

Input : 5
Output : 65

Input : 10
Output : 280

Input : 15
Output : 645

// C++ program to find
// nth octagonal number
#include <bits/stdc++.h>
using namespace std;
 
// Function to calculate
//octagonal number
int octagonal(int n)
{
    // Formula for finding
    // nth octagonal number
    return 3 * n * n - 2 * n;
}
 
// Driver function
int main()
{
    int n = 10;
    cout << n << "th octagonal number :"
         << octagonal(n);
    return 0;
}

// Java program to find
// nth octagonal number
import java.util.*;
import java.lang.*;
 
public class GfG {
 
    // Function to calculate
    //octagonal number
    public static int octagonal(int n)
    {
        // Formula for finding
        // nth octagonal number
        return 3 * n * n - 2 * n;
    }
 
    // Driver function
    public static void main(String argc[])
    {
        int n = 10;
        System.out.println(n + "th octagonal" +
                     " number :" + octagonal(n));
    }
}
 
/* This code is contributed by Sagar Shukla */

# Python program to find
# nth octagonal number
def octagonal(n):
    return 3 * n * n - 2 * n
 
# Driver code
n = 10
print(n, "th octagonal number :",
       octagonal(n))

// C# program to find nth octagonal number
using System;
 
public class GfG {
 
    // Function to calculate
    //octagonal number
    public static int octagonal(int n)
    {
         
        // Formula for finding
        // nth octagonal number
        return 3 * n * n - 2 * n;
    }
 
    // Driver function
    public static void Main()
    {
        int n = 10;
         
        Console.WriteLine(n + "th octagonal"
              + " number :" + octagonal(n));
    }
}
 
/* This code is contributed by Vt_m */

<?php
// PHP program to find
// nth octagonal number
 
 
// Function to calculate
//octagonal number
function octagonal($n)
{
     
    // Formula for finding
    // nth octagonal number
    return 3 * $n * $n - 2 * $n;
}
 
    // Driver Code
    $n = 10;
    echo $n , "th octagonal number :"
                     , octagonal($n);
                      
// This code is contributed by Vt_m .
?>

<script>
 
// JavaScript program to convert
// Binary code to Gray code
 
    // Function to calculate
    //octagonal number
    function octagonal(n)
    {
        // Formula for finding
        // nth octagonal number
        return 3 * n * n - 2 * n;
    }
  
// Driver code                  
        let n = 10;
        document.write(n + "th octagonal" +
                     " number :" + octagonal(n));
    
   // This code is contributed by code_hunt.
</script>

Producción : 
 

10th octagonal number : 280

Tiempo Complejidad: O(1)
Espacio Auxiliar: O(1)
 

Dado el número n, encuentra la serie octogonal hasta n.

También podemos encontrar la serie octogonal. La serie octogonal contiene los puntos en el octágono. 
 

Octagonal series 1, 8, 21, 40, 65, 96, 133, 176, 225, 280, . . .

// C++ program to display the
// octagonal series
#include <bits/stdc++.h>
using namespace std;
 
// Function to display
// octagonal series
void octagonalSeries(int n)
{
    // Formula for finding
    //nth octagonal number
    for (int i = 1; i <= n; i++)
 
        // Formula for computing
        // octagonal number
        cout << (3 * i * i - 2 * i);   
}
 
// Driver function
int main()
{
    int n = 10;
    octagonalSeries(n);
    return 0;
}

// Java program to find
// nth octagonal number
import java.util.*;
import java.lang.*;
  
public class GfG {
  
    // Function to display octagonal series
    public static void octagonalSeries(int n)
    {
        // Formula for finding
        //nth octagonal number
        for (int i = 1; i <= n; i++)
  
            // Formula for computing
            // octagonal number
            System.out.print(3 * i * i - 2 * i);
    }
  
    // Driver function
    public static void main(String argc[])
    {
        int n = 10;
        octagonalSeries(n);
    }
  
    /* This code is contributed by Sagar Shukla */
}

# Python program to find
# nth octagonal number
def octagonalSeries(n):
    for i in range(1, n + 1):
        print(3 * i * i - 2 * i,
                   end = ", ")
 
# Driver code
n = 10
octagonalSeries(n)

// C# program to find
// nth octagonal number
using System;
 
public class GfG {
 
    // Function to display octagonal series
    public static void octagonalSeries(int n)
    {
         
        // Formula for finding
        //nth octagonal number
        for (int i = 1; i <= n; i++)
 
            // Formula for computing
            // octagonal number
            Console.Write(3 * i * i - 2 * i + ", ");
    }
 
    // Driver function
    public static void Main()
    {
        int n = 10;
         
        octagonalSeries(n);
    }
}
 
/* This code is contributed by Vt_m */

<?php
// PHP program to display the
// octagonal series
 
 
// Function to display
// octagonal series
function octagonalSeries($n)
{
     
    // Formula for finding
    // nth octagonal number
    for ($i = 1; $i <= $n; $i++)
 
        // Formula for computing
        // octagonal number
        echo (3 * $i * $i - 2 * $i),",";
}
 
    // Driver Code
    $n = 10;
    octagonalSeries($n);
 
// This code is contributed by Vt_m .
?>

<script>
// Javascript program to display the
// octagonal series
 
 
// Function to display
// octagonal series
function octagonalSeries(n)
{
     
    // Formula for finding
    // nth octagonal number
    for (let i = 1; i <= n; i++)
 
        // Formula for computing
        // octagonal number
        document.write(3 * i * i - 2 * i + ", ");
}
 
    // Driver Code
    let n = 10;
    octagonalSeries(n);
 
// This code is contributed by _saurabh_jaiswal
 
</script>

Producción : 
 

1, 8, 21, 40, 65, 96, 133, 176, 225, 280

Complejidad temporal: O(n)
Espacio auxiliar: O(1)