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// numberint heptagonalNumber(int n){ return ((5 * n * n) - (3 * n)) / 2;}// Drivers Codeint 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// numberint heptagonalNumber(int n){ return ((5 * n * n) - (3 * n)) / 2;}// Drivers Codeint 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 numberimport java.io.*;class GFG {// Function to return // Nth Heptagonal numberstatic int heptagonalNumber(int n){ return ((5 * n * n) - (3 * n)) / 2;}// Driver Codepublic 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 numberdef heptagonalNumber(n) : # Formula to calculate # nth Heptagonal number return ((5 * n * n) - (3 * n)) // 2# Driver Codeif __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 numberusing System;class GFG {// Function to return // Nth Heptagonal numberstatic int heptagonalNumber(int n){ return ((5 * n * n) - (3 * n)) / 2;}// Driver Codepublic 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 numberfunction 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// numberfunction heptagonalNumber(n){ return parseInt(((5 * n * n) - (3 * n)) / 2);}// Drivers Codelet 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
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