Icosihenagonal Number
Given a number N, the task is to find Nth Icosihenagonal number.
An Icosihenagonal number is class of figurate number. It has 21 – sided polygon called Icosihenagon. The n-th Icosihenagonal number counts the 21 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few Icosihenagonal numbers are 1, 21, 60, 118, 195, 291, 406 …
Examples:
Input: N = 2
Output: 21
Explanation:
The second Icosihenagonal number is 21
Input: N = 6
Output: 291
Approach: In mathematics, the Nth Icosihenagonal number is given by the formula:
Below is the implementation of the above approach:
C++
// C++ program to find nth // Icosihenagonal number #include <bits/stdc++.h> using namespace std; // Function to find // Icosihenagonal number int Icosihenagonal_num( int n) { // Formula to calculate nth // Icosihenagonal number return (19 * n * n - 17 * n) / 2; } // Driver Code int main() { int n = 3; cout << Icosihenagonal_num(n) << endl; n = 10; cout << Icosihenagonal_num(n) << endl; return 0; } |
Java
// Java program to find nth // Icosihenagonal number class GFG{ // Function to find // Icosihenagonal number static int Icosihenagonal_num( int n) { // Formula to calculate nth // Icosihenagonal number return ( 19 * n * n - 17 * n) / 2 ; } // Driver Code public static void main(String[] args) { int n = 3 ; System.out.print(Icosihenagonal_num(n) + "\n" ); n = 10 ; System.out.print(Icosihenagonal_num(n) + "\n" ); } } // This code is contributed by Rajput-Ji |
Python3
# Python3 program to find nth # icosihenagonal number # Function to find # icosihenagonal number def Icosihenagonal_num(n): # Formula to calculate nth # icosihenagonal number return ( 19 * n * n - 17 * n) / 2 # Driver Code n = 3 print ( int (Icosihenagonal_num(n))) n = 10 print ( int (Icosihenagonal_num(n))) # This code is contributed by divyeshrabadiya07 |
C#
// C# program to find nth // Icosihenagonal number using System; class GFG{ // Function to find // Icosihenagonal number static int Icosihenagonal_num( int n) { // Formula to calculate nth // Icosihenagonal number return (19 * n * n - 17 * n) / 2; } // Driver Code public static void Main() { int n = 3; Console.Write(Icosihenagonal_num(n) + "\n" ); n = 10; Console.Write(Icosihenagonal_num(n) + "\n" ); } } // This code is contributed by Code_Mech |
Javascript
<script> // Javascript program to find nth // Icosihenagonal number // Function to find // Icosihenagonal number function Icosihenagonal_num(n) { // Formula to calculate nth // Icosihenagonal number return (19 * n * n - 17 * n) / 2; } let n = 3; document.write(Icosihenagonal_num(n) + "</br>" ); n = 10; document.write(Icosihenagonal_num(n)); </script> |
Output:
60 865
Reference: https://en.wikipedia.org/wiki/Polygonal_number