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++ program for above approach #include <bits/stdc++.h> using namespace std;
// Finding the nth octacontagon Number int octacontagonNum( int n)
{ return (78 * n * n - 76 * n) / 2;
} // Driver Code int main()
{ int n = 3;
cout << "3rd octacontagon Number is = "
<< octacontagonNum(n);
return 0;
} // This code is contributed by shivanisinghss2110 |
// C program for above approach #include <stdio.h> #include <stdlib.h> // Finding the nth octacontagon Number int octacontagonNum( int n)
{ return (78 * n * n - 76 * n) / 2;
} // Driver program to test above function int main()
{ int n = 3;
printf ( "3rd octacontagon Number is = %d" ,
octacontagonNum(n));
return 0;
} |
// Java program for above approach import java.util.*;
class GFG{
// Finding the nth octacontagon Number static int octacontagonNum( int n)
{ return ( 78 * n * n - 76 * n) / 2 ;
} // Driver Code public static void main(String args[])
{ int n = 3 ;
System.out.print( "3rd octacontagon Number is = " +
octacontagonNum(n));
} } // This code is contributed by Akanksha_Rai |
# Python3 program for above approach # Finding the nth octacontagon number def octacontagonNum(n):
return ( 78 * n * n - 76 * n) / / 2
# Driver code n = 3
print ( "3rd octacontagon Number is = " ,
octacontagonNum(n))
# This code is contributed by divyamohan123 |
// C# program for above approach using System;
class GFG{
// Finding the nth octacontagon Number static int octacontagonNum( int n)
{ return (78 * n * n - 76 * n) / 2;
} // Driver Code public static void Main()
{ int n = 3;
Console.Write( "3rd octacontagon Number is = " +
octacontagonNum(n));
} } // This code is contributed by Akanksha_Rai |
<script> // Javascript program for above approach // Finding the nth octacontagon Number function octacontagonNum(n)
{ return (78 * n * n - 76 * n) / 2;
} // Driver Code 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