Octahedral Number
Given a number n, the task is to find n-th octahedral number.
An octahedral number belongs to a figurate number and it is the number of spheres in an octahedron built from closely packed spheres. First, a few octahedral numbers (where n = 0, 1, 2, 3…….) are 0, 1, 6, 19, and so on.
Examples :
Input: 4
Output: 44Input: 8
Output: 344
Formula for nth octahedral number:
n * (2n2+1) / 3
C++
// C++ program to find nth // octahedral number #include <bits/stdc++.h> using namespace std; // Function to find // octahedral number int octahedral_num( int n) { // Formula to calculate nth // octahedral number return n * (2 * n * n + 1) / 3; } // Drivers code int main() { int n = 5; // print result cout << n << "th Octahedral number: " ; cout << octahedral_num(n); return 0; } |
Java
// Java program to find nth octahedral // number import java.io.*; class GFG { // Function to find octahedral number static int octahedral_num( int n) { // Formula to calculate nth // octahedral number // and return it into main function. return n * ( 2 * n * n + 1 ) / 3 ; } // Driver Code public static void main(String[] args) { int n = 5 ; // print result System.out.print(n + "th Octahedral" + " number: " ); System.out.println(octahedral_num(n)); } } |
Python3
# Python 3 program to find nth # octahedral number # Function to find # octahedral number def octahedral_num(n) : # Formula to calculate nth # octahedral number return n * ( 2 * n * n + 1 ) / / 3 # Driver Code if __name__ = = '__main__' : n = 5 print (n, "th Octahedral number: " , octahedral_num(n)) # This code is contributed ajit. |
C#
// C# program to find nth // Octahedral number using System; class GFG { // Function to find // octahedral number static int octahedral_num( int n) { // Formula to calculate // nth octahedral number // and return it into // main function. return n * (2 * n * n + 1) / 3; } // Driver Code static public void Main () { int n = 5; // print result Console.Write(n + "th Octahedral" + " number: " ); Console.WriteLine(octahedral_num(n)); } } // This code is Contributed by m_kit |
PHP
<?php // PHP program to find nth // octahedral number // Function to find // octahedral number function octahedral_num( $n ) { // Formula to calculate nth // octahedral number // and return it into main function. return $n * (2 * $n * $n + 1) / 3; } // Drivers Code $n = 5; // print result echo $n , "th Octahedral number: " ; echo octahedral_num( $n ); ?> |
Javascript
<script> // JavaScript program to find nth // octahedral number // Function to find // octahedral number function octahedral_num( n) { // Formula to calculate nth // octahedral number // and return it into main function. return n * (2 * n * n + 1) / 3; } // Drivers Code let n = 5; // print result document.write( n+ "th Octahedral number: " ); document.write(octahedral_num(n)); // This code is contributed by Bobby </script> |
Output
5th Octahedral number: 85
Time Complexity: O(1) because constant operations are being performed
Auxiliary Space: O(1)
Reference: https://en.wikipedia.org/wiki/Octahedral_number
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