Chiliagon Number

Last Updated : 13 Apr, 2021

Given a number N, the task is to find N^th chiliagon number.

A chiliagon number is class of figurate number. It has 1000 – sided polygon called chiliagon. The N-th chiliagon number count’s the 1000 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few chiliagonol numbers are 1, 1000, 2997, 5992 …

Examples:

Input: N = 2
Output: 1000
Explanation:
The second chiliagonol number is 1000.
Input: N = 3
Output: 2997

Approach: The N-th chiliagon number is given by the formula:

Nth term of s sided polygon = $\frac{((s-2)n^2 - (s-4)n)}{2}$
Therefore Nth term of 1000 sided polygon is

$Tn =\frac{((1000-2)n^2 - (1000-4)n)}{2} =\frac{(998n^2 - 996n)}{2}$

Below is the implementation of the above approach:

C++

// C++ program for above approach
#include <bits/stdc++.h>
using namespace std;
 
// Finding the nth chiliagon Number
int chiliagonNum(int n)
{
    return (998 * n * n - 996 * n) / 2;
}
 
// Driver Code
int main()
{
    int n = 3;
    cout <<"3rd chiliagon Number is = "
         << chiliagonNum(n);
 
    return 0;
}
 
// This code is contributed by shivanisinghss2110

C

// C program for above approach
#include <stdio.h>
#include <stdlib.h>
 
// Finding the nth chiliagon Number
int chiliagonNum(int n)
{
    return (998 * n * n - 996 * n) / 2;
}
 
// Driver program to test above function
int main()
{
    int n = 3;
    printf("3rd chiliagon Number is = %d",
           chiliagonNum(n));
 
    return 0;
}

Java

// Java program for the above approach
class GFG{
 
// Finding the nth chiliagon number
static int chiliagonNum(int n)
{
    return (998 * n * n - 996 * n) / 2;
}
 
// Driver code
public static void main(String[] args)
{
    int n = 3;
    System.out.println("3rd chiliagon Number is = " +
                                    chiliagonNum(n));
}
}
 
// This code is contributed by rutvik_56

Python3

# Python3 program for above approach
 
# Finding the nth chiliagon Number
def chiliagonNum(n):
 
    return (998 * n * n - 996 * n) // 2;
 
# Driver Code
n = 3;
print("3rd chiliagon Number is = ",
                  chiliagonNum(n));
 
# This code is contributed by Akanksha_Rai

C#

// C# program for the above approach
using System;
class GFG{
 
// Finding the nth chiliagon number
static int chiliagonNum(int n)
{
    return (998 * n * n - 996 * n) / 2;
}
 
// Driver code
public static void Main()
{
    int n = 3;
    Console.Write("3rd chiliagon Number is = " +
                               chiliagonNum(n));
}
}
 
// This code is contributed by Akanksha_Rai

Javascript

<script>
 
// javascript program for above approach
 
 
// Finding the nth chiliagon Number
function chiliagonNum( n)
{
    return (998 * n * n - 996 * n) / 2;
}
 
// Driver code
let n = 3;
document.write("3rd chiliagon Number is "
+ chiliagonNum(n));
 
// This code contributed by gauravrajput1
 
</script>

Output:

3rd chiliagon Number is = 2997

Time Complexity: O(1)

Auxiliary Space: O(1)

Reference: https://en.wikipedia.org/wiki/Chiliagon

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Chiliagon Number

C++

C

Java

Python3

C#

Javascript

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