Icosihenagonal Number
Last Updated :
17 Mar, 2021
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++
#include <bits/stdc++.h>
using namespace std;
int Icosihenagonal_num( int n)
{
return (19 * n * n - 17 * n) / 2;
}
int main()
{
int n = 3;
cout << Icosihenagonal_num(n) << endl;
n = 10;
cout << Icosihenagonal_num(n) << endl;
return 0;
}
|
Java
class GFG{
static int Icosihenagonal_num( int n)
{
return ( 19 * n * n - 17 * n) / 2 ;
}
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" );
}
}
|
Python3
def Icosihenagonal_num(n):
return ( 19 * n * n - 17 * n) / 2
n = 3
print ( int (Icosihenagonal_num(n)))
n = 10
print ( int (Icosihenagonal_num(n)))
|
C#
using System;
class GFG{
static int Icosihenagonal_num( int n)
{
return (19 * n * n - 17 * n) / 2;
}
public static void Main()
{
int n = 3;
Console.Write(Icosihenagonal_num(n) + "\n" );
n = 10;
Console.Write(Icosihenagonal_num(n) + "\n" );
}
}
|
Javascript
<script>
function Icosihenagonal_num(n)
{
return (19 * n * n - 17 * n) / 2;
}
let n = 3;
document.write(Icosihenagonal_num(n) + "</br>" );
n = 10;
document.write(Icosihenagonal_num(n));
</script>
|
Reference: https://en.wikipedia.org/wiki/Polygonal_number
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