# 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 countâ€™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 = 2Output:26Explanation:

The second Icosihexagonol number is 26.Input:N = 3Output: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` |

## 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;` `}` |

## 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` |

## 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` |

## 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` |

## Javascript

`<script>` `// javascript program for above approach` `// Finding the nth Icosihexagonal Number` `function` `IcosihexagonalNum( n)` `{` ` ` `return` `(24 * n * n - 22 * n) / 2;` `}` `// Driver code` `let n = 3;` `document.write(` `"3rd Icosihexagonal Number is "` `+ IcosihexagonalNum(n));` `// This code contributed by gauravrajput1` `</script>` |

**Output:**

3rd Icosihexagonal Number is = 75

**Time Complexity: **O(1)

**Auxiliary Space: **O(1)

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

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