Given a number n, the task is to find Nth heptagonal number. A Heptagonal number represents heptagon and belongs to a figurative number. Heptagonal has seven angles, seven vertices, and seven-sided polygon.
Examples :
Input : 2
Output :7
Input :15
Output :540
Few Heptagonal numbers are :
1, 7, 18, 34, 55, 81, 112, 148, 189, 235………..
A formula to calculate Nth Heptagonal number:
C++
// C++ program to find the // nth Heptagonal number #include <iostream> using namespace std;
// Function to return Nth Heptagonal // number int heptagonalNumber( int n)
{ return ((5 * n * n) - (3 * n)) / 2;
} // Drivers Code int main()
{ int n = 2;
cout << heptagonalNumber(n) << endl;
n = 15;
cout << heptagonalNumber(n) << endl;
return 0;
} |
C
// C program to find the // nth Heptagonal number #include <stdio.h> // Function to return Nth Heptagonal // number int heptagonalNumber( int n)
{ return ((5 * n * n) - (3 * n)) / 2;
} // Drivers Code int main()
{ int n = 2;
printf ( "%d\n" ,heptagonalNumber(n));
n = 15;
printf ( "%d\n" ,heptagonalNumber(n));
return 0;
} // This code is contributed by kothavvsaakash. |
Java
// Java program to find the // nth Heptagonal number import java.io.*;
class GFG
{ // Function to return // Nth Heptagonal number static int heptagonalNumber( int n)
{ return (( 5 * n * n) - ( 3 * n)) / 2 ;
} // Driver Code public static void main (String[] args)
{ int n = 2 ;
System.out.println(heptagonalNumber(n));
n = 15 ;
System.out.println(heptagonalNumber(n));
} } // This code is contributed by anuj_67. |
Python3
# Program to find nth # Heptagonal number # Function to find # nth Heptagonal number def heptagonalNumber(n) :
# Formula to calculate
# nth Heptagonal number
return (( 5 * n * n) -
( 3 * n)) / / 2
# Driver Code if __name__ = = '__main__' :
n = 2
print (heptagonalNumber(n))
n = 15
print (heptagonalNumber(n))
# This code is contributed # by ajit |
C#
// C# program to find the // nth Heptagonal number using System;
class GFG
{ // Function to return // Nth Heptagonal number static int heptagonalNumber( int n)
{ return ((5 * n * n) -
(3 * n)) / 2;
} // Driver Code public static void Main ()
{ int n = 2;
Console.WriteLine(heptagonalNumber(n));
n = 15;
Console.WriteLine(heptagonalNumber(n));
} } // This code is contributed by anuj_67. |
PHP
<?php // PHP program to find the // nth Heptagonal number // Function to return Nth // Heptagonal number function heptagonalNumber( $n )
{ return ((5 * $n * $n ) -
(3 * $n )) / 2;
} // Driver Code $n = 2;
echo heptagonalNumber( $n ), "\n" ;
$n = 15;
echo heptagonalNumber( $n );
// This code is contributed // by anuj_67. ?> |
Javascript
<script> // Javascript program to find the // nth Heptagonal number // Function to return Nth Heptagonal // number function heptagonalNumber(n)
{ return parseInt(((5 * n * n) - (3 * n)) / 2);
} // Drivers Code let n = 2; document.write(heptagonalNumber(n) + "<br>" );
n = 15; document.write(heptagonalNumber(n) + "<br>" );
// This code is contributed by rishavmahato348. </script> |
Output :
7 540
Time Complexity: O(1), since there is no loop or recursion.
Auxiliary Space: O(1), since no extra space has been taken.
Reference: https://en.wikipedia.org/wiki/Heptagonal_number