Icosagonal number
Given a number n, the task is to find the nth Icosagonal number.
An Icosagonal number is the 20-gon is a twenty-sided polygon. The number derived from the figurative class. There are different pattern series number in this number. The dots are countable, arrange in a specific way of position and create a diagram. All the dots have a common dots points, all others dots are connected to this points and except this common point the dots connected to their i-th dots with their respective successive layer.
Examples :
Input : 3
Output :57
Input :8
Output :512
Formula for nth icosagonal number:
C++
// C++ program to find // nth Icosagonal number #include <bits/stdc++.h> using namespace std; // Function to calculate Icosagonal number int icosagonal_poly( long int n) { // Formula for finding // nth Icosagonal number return (18 * n * n - 16 * n) / 2; } // Drivers code int main() { long int n = 7; cout << n << "th Icosagonal number :" << icosagonal_poly(n); return 0; } |
C
// C program to find // nth Icosagonal number #include <stdio.h> // Function to calculate Icosagonal number int icosagonal_poly( long int n) { // Formula for finding // nth Icosagonal number return (18 * n * n - 16 * n) / 2; } // Drivers code int main() { long int n = 7; printf ( "%ldth Icosagonal number : %d" ,n,icosagonal_poly(n)); return 0; } |
Java
// Java program to find // nth Icosagonal number import java.io.*; class GFG { // Function to calculate Icosagonal number static int icosagonal_poly( int n) { // Formula for finding // nth Icosagonal number return ( 18 * n * n - 16 * n) / 2 ; } // Drivers code public static void main (String[] args) { int n = 7 ; System.out.print (n + "th Icosagonal number :" ); System.out.println(icosagonal_poly(n)); } } // This code is contributed by aj_36 |
Python 3
# Python 3 program to find # nth Icosagonal number # Function to calculate # Icosagonal number def icosagonal_poly(n) : # Formula for finding # nth Icosagonal number return ( 18 * n * n - 16 * n) / / 2 # Driver Code if __name__ = = '__main__' : n = 7 print (n, "th Icosagonal number : " , icosagonal_poly(n)) # This code is contributed m_kit |
C#
// C# program to find // nth Icosagonal number using System; class GFG { // Function to calculate // Icosagonal number static int icosagonal_poly( int n) { // Formula for finding // nth Icosagonal number return (18 * n * n - 16 * n) / 2; } // Driver code static public void Main () { int n = 7; Console.Write(n + "th Icosagonal " + "number :" ); Console.WriteLine(icosagonal_poly(n)); } } // This code is contributed by ajit |
PHP
<?php // PHP program to find // nth Icosagonal number // Function to calculate // Icosagonal number function icosagonal_poly( $n ) { // Formula for finding // nth Icosagonal number return (18 * $n * $n - 16 * $n ) / 2; } // Driver Code $n = 7; echo $n , "th Icosagonal number :" , icosagonal_poly( $n ); // This code is contributed by ajit ?> |
Javascript
<script> // Javascript program to find nth Icosagonal number // Function to calculate // Icosagonal number function icosagonal_poly(n) { // Formula for finding // nth Icosagonal number return (18 * n * n - 16 * n) / 2; } let n = 7; document.write(n + "th Icosagonal number :" ); document.write(icosagonal_poly(n)); </script> |
Output :
7th Icosagonal number :385
Time Complexity: O(1)
Auxiliary Space: O(1)
Reference: https://en.wikipedia.org/wiki/Polygonal_number