# Icosihexagonal Number

Given a number **N**, the task is to find **N ^{th}** Icosihexagon number.

An Icosihexagon number is class of figurate number. It has 26 – sided polygon called Icosihexagon. The N-th Icosihexagonal number count’s the 26 number of dots and all other dots are surrounding with a common sharing corner and make a pattern. The first few Icosihexagonol numbers are

1, 26, 75, 148 …

**Examples:**

Input:N = 2

Output:26

Explanation:

The second Icosihexagonol number is 26.

Input:N = 3

Output:75

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

- Nth term of s sided polygon =
- Therefore Nth term of 26 sided polygon is

Below is the implementation of the above approach:

## C++

`// C++ program for above approach ` `#include <bits/stdc++.h> ` `using` `namespace` `std; ` ` ` `// Finding the nth Icosihexagonal Number ` `int` `IcosihexagonalNum(` `int` `n) ` `{ ` ` ` `return` `(24 * n * n - 22 * n) / 2; ` `} ` ` ` `// Driver Code ` `int` `main() ` `{ ` ` ` `int` `n = 3; ` ` ` `cout << ` `"3rd Icosihexagonal Number is = "` ` ` `<< IcosihexagonalNum(n); ` ` ` ` ` `return` `0; ` `} ` ` ` `// This code is contributed by Code_Mech ` |

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## C

`// C program for above approach ` `#include <stdio.h> ` `#include <stdlib.h> ` ` ` `// Finding the nth Icosihexagonal Number ` `int` `IcosihexagonalNum(` `int` `n) ` `{ ` ` ` `return` `(24 * n * n - 22 * n) / 2; ` `} ` ` ` `// Driver program to test above function ` `int` `main() ` `{ ` ` ` `int` `n = 3; ` ` ` `printf` `(` `"3rd Icosihexagonal Number is = %d"` `, ` ` ` `IcosihexagonalNum(n)); ` ` ` ` ` `return` `0; ` `} ` |

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## Java

`// Java program for above approach ` `class` `GFG{ ` ` ` `// Finding the nth icosihexagonal number ` `public` `static` `int` `IcosihexagonalNum(` `int` `n) ` `{ ` ` ` `return` `(` `24` `* n * n - ` `22` `* n) / ` `2` `; ` `} ` ` ` `// Driver code ` `public` `static` `void` `main(String[] args) ` `{ ` ` ` `int` `n = ` `3` `; ` ` ` ` ` `System.out.println(` `"3rd Icosihexagonal Number is = "` `+ ` ` ` `IcosihexagonalNum(n)); ` `} ` `} ` ` ` `// This code is contributed by divyeshrabadiya07 ` |

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## Python3

`# Python3 program for above approach ` ` ` `# Finding the nth Icosihexagonal Number ` `def` `IcosihexagonalNum(n): ` ` ` ` ` `return` `(` `24` `*` `n ` `*` `n ` `-` `22` `*` `n) ` `/` `/` `2` ` ` `# Driver Code ` `n ` `=` `3` `print` `(` `"3rd Icosihexagonal Number is = "` `, ` ` ` `IcosihexagonalNum(n)) ` ` ` `# This code is contributed by divyamohan123 ` |

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## C#

`// C# program for above approach ` `using` `System; ` ` ` `class` `GFG{ ` ` ` `// Finding the nth icosihexagonal number ` `public` `static` `int` `IcosihexagonalNum(` `int` `n) ` `{ ` ` ` `return` `(24 * n * n - 22 * n) / 2; ` `} ` ` ` `// Driver code ` `public` `static` `void` `Main(String[] args) ` `{ ` ` ` `int` `n = 3; ` ` ` ` ` `Console.WriteLine(` `"3rd Icosihexagonal Number is = "` `+ ` ` ` `IcosihexagonalNum(n)); ` `} ` `} ` ` ` `// This code is contributed by 29AjayKumar ` |

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**Output:**

3rd Icosihexagonal Number is = 75

**Reference:** https://en.wikipedia.org/wiki/Icosihexagon

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