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# Icosikaiheptagonal Number

• Last Updated : 23 Jun, 2021

Given a number N, the task is to find Nth icosikaiheptagonal number.

An icosikaiheptagonal number is a class of figurate numbers. It has 27 – sided polygon called icosikaiheptagon. The N-th icosikaiheptagonal number count’s the 27 number of dots and all other dots are surrounding with a common sharing corner and make a pattern. The first few icosikaiheptagonol numbers are 1, 27, 78, 154 …

Examples:

Input: N = 2
Output: 27
Explanation:
The second icosikaiheptagonol number is 27.
Input: N = 3
Output: 78

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

• Nth term of s sided polygon =

• Therefore Nth term of 27 sided polygon is

•

Below is the implementation of the above approach:

## C++

 // C++ program to find N-th// icosikaiheptagonal number#include  using namespace std;// Function to find the nth// icosikaiheptagonal Numberint icosikaiheptagonalNum(int n){    return (25 * n * n - 23 * n) / 2;} // Driver codeint main(){    int n = 3;     cout << "3rd icosikaiheptagonal Number is "         << icosikaiheptagonalNum(n);     return 0;}

## Java

 // Java program to find N-th// icosikaiheptagonal numberclass GFG{ // Function to find the nth// icosikaiheptagonal numberstatic int icosikaiheptagonalNum(int n){    return (25 * n * n - 23 * n) / 2;} // Driver codepublic static void main(String[] args){    int n = 3;    System.out.print("3rd icosikaiheptagonal Number is " +                                icosikaiheptagonalNum(n));}} // This code is contributed by shubham

## Python3

 # Python3 program to find N-th# icosikaiheptagonal number # Function to find the nth# icosikaiheptagonal Numberdef icosikaiheptagonalNum(n):     return (25 * n * n - 23 * n) // 2; # Driver coden = 3;print("3rd icosikaiheptagonal Number is ",                icosikaiheptagonalNum(n)); # This code is contributed by Code_Mech

## C#

 // C# program to find N-th// icosikaiheptagonal numberusing System; class GFG{ // Function to find the nth// icosikaiheptagonal numberstatic int icosikaiheptagonal(int n){    return (25 * n * n - 23 * n) / 2;} // Driver codepublic static void Main(String[] args){    int n = 3;         Console.Write("3rd icosikaiheptagonal Number is " +                                icosikaiheptagonal(n));}} // This code is contributed by shivanisinghss2110

## Javascript

 
Output:
3rd icosikaiheptagonal Number is 78

Time Complexity: O(1)

Auxiliary Space: O(1)

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

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