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++ 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 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 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# 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 |
<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