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• Last Updated : 09 Apr, 2021

Given a number n, find the nth Centered Hexadecagonal Number.
A Centered Hexadecagonal number represents a dot in the centre and other dots around it in successive hexadecagonal(16 sided polygon) layers.

The first few Centered Hexadecagonal numbers are:
1, 17, 49, 97, 161, 241, 337, 449, 577, 721, 881………………….

Examples :

```Input :  3
Output : 49

Input : 10
Output : 721```

In mathematics, Centered hexadecagonal number for the n-th term is given by :

Below is the basic implementation of the above idea:

## C++

 `// C++ Program to find``// nth centered hexadecagonal``// number``#include ``using` `namespace` `std;` `// centered hexadecagonal function``int` `center_hexadecagonal_num(``long` `int` `n)``{``    ``// Formula to calculate nth``    ``// centered hexadecagonal number``    ``return` `8 * n * n - 8 * n + 1;``}` `// Driver Code``int` `main()``{``    ``long` `int` `n = 2;``    ``cout << n << ``"th centered hexadecagonal number : "``                    ``<< center_hexadecagonal_num(n);``    ``cout << endl;``    ``n = 12;``    ``cout << n << ``"th centered hexadecagonal numbe : "``                    ``<< center_hexadecagonal_num(n);` `    ``return` `0;``}`

## Java

 `// Java Program to find nth``// centered hexadecagonal number``import` `java.io.*;` `class` `GFG``{``    ``// centered hexadecagonal function``    ``static` `int` `center_hexadecagonal_num(``int` `n)``    ``{``        ``// Formula to calculate nth``        ``// centered hexadecagonal number``        ``return` `8` `* n * n -``               ``8` `* n + ``1``;``    ``}``    ` `    ``// Driver Code``    ``public` `static` `void` `main(String args[])``    ``{``        ``int` `n = ``2``;``        ``System.out.print(n + ``"th centered "` `+``                    ``"hexadecagonal number: "``);``        ``System.out.println(center_hexadecagonal_num(n));``        ` `        ``n = ``12``;``        ``System.out.print(n + ``"th centered "` `+``                    ``"hexadecagonal number: "``);``        ``System.out.println(center_hexadecagonal_num(n));``    ``}``}` `// This code is contributed by ajit.`

## Python3

 `# Program to find nth``# centered hexadecagonal``# number` `# centered hexadecagonal``# function``def` `center_hexadecagonal_num(n):``    ` `    ``# Formula to calculate``    ``# nth centered hexadecagonal``    ``# number``    ``return` `8` `*` `n ``*` `n ``-` `8` `*` `n ``+` `1` `# Driver Code``if` `__name__ ``=``=` `'__main__'` `:``        ` `    ``n ``=` `2``    ``print``(n,``"nd centered hexadecagonal "` `+``                              ``"number : "``,``              ``center_hexadecagonal_num(n))``    ``n ``=` `12``    ``print``(n,``"th centered hexadecagonal "` `+``                              ``"number : "``,``              ``center_hexadecagonal_num(n))``                ` `# This code is contributed``# by akt_mit`

## C#

 `// C# Program to find nth``// centered hexadecagonal number``using` `System;` `class` `GFG``{``    ` `    ``// centered hexadecagonal``    ``// function``    ``static` `int` `center_hexadecagonal_num(``int` `n)``    ``{``        ``// Formula to calculate nth``        ``// centered hexadecagonal number``        ``return` `8 * n * n -``               ``8 * n + 1;``    ``}``    ` `    ``// Driver Code``    ``static` `public` `void` `Main ()``    ``{``        ``int` `n = 2;``        ``Console.Write(n + ``"th centered "` `+``                    ``"hexadecagonal number: "``);``        ``Console.WriteLine(center_hexadecagonal_num(n));``        ` `        ``n = 12;``        ``Console.Write(n + ``"th centered "` `+``                    ``"hexadecagonal number: "``);``        ``Console.WriteLine(center_hexadecagonal_num(n));``    ``}``}` `// This code is contributed by m_kit`

## PHP

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## Javascript

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Output :

```2th centered hexadecagonal number : 17
12th centered hexadecagonal numbe : 1057```

References:
http://oeis.org/A069129

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