Icosikaienneagonal Number

An icosikaienneagonal number is a class of figurate numbers. It has 29 – sided polygon called icosikaienneagon. The N-th icosikaienneagonal number count’s the 29 number of dots and all other dots are surrounding with a common sharing corner and make a pattern.
The first few icosikaienneagonol numbers are 

1, 29, 84, 166 … 

Find the N^th icosikaienneagonal number

Given a number N, the task is to find N^th icosikaienneagonal number.
Examples:

Input: N = 2 
Output: 29 
Explanation:
The second icosikaienneagonol number is 29. 
Input: N = 3 
Output: 84 

Approach:

• In mathematics, the N-th s-sided polygon number is given by the formula: 
  
  
• Therefore Nth term of 29 sided polygon is 
  

• 
  

Below is the implementation of the above approach:

C++

// C++ implementation for
// above approach

#include <iostream>
using namespace std;

// Function to Find the Nth
// icosikaienneagonal Number
int icosikaienneagonalNum(int n)
{
    return (27 * n * n - 25 * n) / 2;
}

// Driver Code
int main()
{
    int n = 3;
    cout << icosikaienneagonalNum(n);

    return 0;
}

Java

// Java implementation for
// above approach
class GFG{

// Function to Find the Nth
// icosikaienneagonal Number
static int icosikaienneagonalNum(int n)
{
    return (27 * n * n - 25 * n) / 2;
}

// Driver Code
public static void main(String args[])
{
    int n = 3;
    System.out.print(icosikaienneagonalNum(n));
}
}

// This code is contributed by Code_Mech

Python 3

# Python3 implementation for
# above approach

# Function to Find the Nth
# icosikaienneagonal Number
def icosikaienneagonalNum(n):
    return (27 * n * n - 25 * n) // 2

# Driver Code

# Given N
N = 3
print(icosikaienneagonalNum(N))

# This code is contributed by Vishal Maurya

C#

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

// Function to Find the Nth
// icosikaienneagonal Number
static int icosikaienneagonalNum(int n)
{
    return (27 * n * n - 25 * n) / 2;
}

// Driver Code
public static void Main()
{
    int n = 3;
    Console.Write(icosikaienneagonalNum(n));
}
}

// This code is contributed by Code_Mech

Javascript

<script>
// Javascript implementation for
// above approach


    // Function to Find the Nth
    // icosikaienneagonal Number
    function icosikaienneagonalNum( n) {
        return (27 * n * n - 25 * n) / 2;
    }

    // Driver Code

    let n = 3;
    document.write(icosikaienneagonalNum(n));

// This code is contributed by Rajput-Ji
</script>

Output:

84

Time Complexity: O(1)

Auxiliary Space: O(1)