Octacontagon Number
Last Updated :
07 Oct, 2021
Given a number N, the task is to find Nth Octacontagon number.
A Octacontagon number is class of figurate number. It has 80 – sided polygon called octacontagon. The N-th octacontagon number count’s the 80 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few octacontagonol numbers are 1, 80, 237, 472 …
Examples:
Input: N = 2
Output: 80
Explanation:
The second octacontagonol number is 80.
Input: N = 3
Output: 237
Approach: The N-th octacontagon number is given by the formula:
- Nth term of s sided polygon =
- Therefore Nth term of 80 sided polygon is
Below is the implementation of the above approach:
C++
#include <bits/stdc++.h>
using namespace std;
int octacontagonNum( int n)
{
return (78 * n * n - 76 * n) / 2;
}
int main()
{
int n = 3;
cout << "3rd octacontagon Number is = "
<< octacontagonNum(n);
return 0;
}
|
C
#include <stdio.h>
#include <stdlib.h>
int octacontagonNum( int n)
{
return (78 * n * n - 76 * n) / 2;
}
int main()
{
int n = 3;
printf ( "3rd octacontagon Number is = %d" ,
octacontagonNum(n));
return 0;
}
|
Java
import java.util.*;
class GFG{
static int octacontagonNum( int n)
{
return ( 78 * n * n - 76 * n) / 2 ;
}
public static void main(String args[])
{
int n = 3 ;
System.out.print( "3rd octacontagon Number is = " +
octacontagonNum(n));
}
}
|
Python3
def octacontagonNum(n):
return ( 78 * n * n - 76 * n) / / 2
n = 3
print ( "3rd octacontagon Number is = " ,
octacontagonNum(n))
|
C#
using System;
class GFG{
static int octacontagonNum( int n)
{
return (78 * n * n - 76 * n) / 2;
}
public static void Main()
{
int n = 3;
Console.Write( "3rd octacontagon Number is = " +
octacontagonNum(n));
}
}
|
Javascript
<script>
function octacontagonNum(n)
{
return (78 * n * n - 76 * n) / 2;
}
var n = 3;
document.write( "3rd octacontagon Number is = " + octacontagonNum(n));
</script>
|
Output: 3rd octacontagon Number is = 237
Time Complexity: O(1)
Auxiliary Space: O(1)
Reference: https://en.wikipedia.org/wiki/Octacontagon
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