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: 44
Input: 8
Output: 344
Formula for nth octahedral number:
n * (2n2+1) / 3
C++
#include <bits/stdc++.h>
using namespace std;
int octahedral_num( int n)
{
return n * (2 * n * n + 1) / 3;
}
int main()
{
int n = 5;
cout << n << "th Octahedral number: " ;
cout << octahedral_num(n);
return 0;
}
|
Java
import java.io.*;
class GFG {
static int octahedral_num( int n)
{
return n * ( 2 * n * n + 1 ) / 3 ;
}
public static void main(String[] args)
{
int n = 5 ;
System.out.print(n + "th Octahedral"
+ " number: " );
System.out.println(octahedral_num(n));
}
}
|
Python3
def octahedral_num(n) :
return n * ( 2 * n * n + 1 ) / / 3
if __name__ = = '__main__' :
n = 5
print (n, "th Octahedral number: "
, octahedral_num(n))
|
C#
using System;
class GFG
{
static int octahedral_num( int n)
{
return n * (2 * n *
n + 1) / 3;
}
static public void Main ()
{
int n = 5;
Console.Write(n + "th Octahedral"
+ " number: " );
Console.WriteLine(octahedral_num(n));
}
}
|
PHP
<?php
function octahedral_num( $n )
{
return $n * (2 * $n * $n + 1) / 3;
}
$n = 5;
echo $n , "th Octahedral number: " ;
echo octahedral_num( $n );
?>
|
Javascript
<script>
function octahedral_num( n)
{
return n * (2 * n * n + 1) / 3;
}
let n = 5;
document.write( n+ "th Octahedral number: " );
document.write(octahedral_num(n));
</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
Last Updated :
16 Dec, 2022
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