Icosikaipentagon Number

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

An icosikaipentagon number is class of figurate number. It has 25- sided polygon called icosikaipentagon. The N-th icosikaipentagon number count’s the 25 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few icosikaipentagonol numbers are 1, 25, 72, 142 …

Examples:

Input: N = 2 
Output: 25 
Explanation:
The second icosikaipentagonol number is 25. 

Input: N = 3 
Output: 72 

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

• N-th term of S sided polygon = 
• Therefore N-th term of 25 sided polygon is given by:

Below is the implementation of the above approach:

C++

// C++ program to find the N-th
// Icosikaipentagon Number

#include <bits/stdc++.h>
using namespace std;

// Function to find the N-th
// icosikaipentagon Number
int icosikaipentagonNum(int N)
{
    return (23 * N * N - 21 * N)
           / 2;
}

// Driver code
int main()
{
    int n = 3;
    cout << "3rd icosikaipentagon Number is "
         << icosikaipentagonNum(n);

    return 0;
}

Java

// Java program to find N-th
// icosikaipentagon number
class GFG{

// Function to find the nth
// icosikaipentagon number
static int icosikaipentagonNum(int N)
{
    return (23 * N * N - 21 * N) / 2;
}

// Driver code
public static void main(String[] args)
{
    int n = 3;
    System.out.print("3rd icosikaipentagon Number is " +
                                icosikaipentagonNum(n));
}
}

// This code is contributed by shubham

Python3

# Python3 program to find the N-th
# icosikaipentagon number

# Function to find the N-th
# icosikaipentagon number
def icosikaipentagonNum(N):

    return (23 * N * N - 21 * N) // 2

# Driver code
n = 3
print("3rd icosikaipentagon Number is ",
                 icosikaipentagonNum(n))

# This code is contributed by yatinagg

C#

// C# program for the above approach
using System;
class GFG{

// Finding the nth chiliagon number
static int Icosikaipentagon(int n)
{
    return (23 * n * n - 21 * n) / 2;
}

// Driver code
public static void Main()
{
    int n = 3;
    Console.Write("3rd Icosikaipentagon Number is = " +
                                  Icosikaipentagon(n));
}
}

// This code is contributed by shivanisinghss2110

Javascript

<script>
// Javascript program to find the N-th
// Icosikaipentagon Number

// Function to find the N-th
// icosikaipentagon Number
function icosikaipentagonNum(N)
{
    return parseInt((23 * N * N - 21 * N)
           / 2);
}

// Driver code
let n = 3;
document.write("3rd icosikaipentagon Number is "
    + icosikaipentagonNum(n));

    // This code is contributed by rishavmahato348.
</script>

Output:

3rd icosikaipentagon Number is 72

Time Complexity: O(1)

Auxiliary Space: O(1)

Reference: http://www.2dcurves.com/line/linep.html