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# Centered tridecagonal number

• Last Updated : 16 Jul, 2021

Given a number n, the task is to find the nth Centered Tridecagonal Number.
A Centered tridecagonal number represents a dot at the center and other dots surrounding the center dot
in the successive tridecagonal(13 sided polygon) layer.

Examples :

Input : 2
Output : 14

Input : 9
Output : 469 Formula for nth Centered tridecagonal number:

` `

## C++

 `// C++ Program to find nth``// centered tridecagonal number``#include ``using` `namespace` `std;` `// Function to find nth centered``// tridecagonal number``int` `centeredTridecagonalNum(``long` `int` `n)``{``    ``// Formula to calculate nth``    ``// centered tridecagonal number``    ``return` `(13 * n * (n - 1) + 2) / 2;``}` `// Drivers code``int` `main()``{``    ``long` `int` `n = 3;``    ``cout << centeredTridecagonalNum(n);``    ``cout << endl;``    ``n = 10;``    ``cout << centeredTridecagonalNum(n);` `    ``return` `0;``}`

## Java

 `// Java Program to find nth``// centered tridecagonal number``import` `java.io.*;` `class` `GFG``{` `// Function to find nth centered``// tridecagonal number``static` `long` `centeredTridecagonalNum(``long` `n)``{``    ``// Formula to calculate nth``    ``// centered tridecagonal number``    ``return` `(``13` `* n * (n - ``1``) + ``2``) / ``2``;``}` `// Driver Code``public` `static` `void` `main (String[] args)``{``    ``long` `n = ``3``;``    ``System.out.println(centeredTridecagonalNum(n));``    ``n = ``10``;``    ``System.out.println(centeredTridecagonalNum(n));``}``}` `// This code is contributed by anuj_67.`

## Python3

 `# Program to find nth centered``# tridecagonal number` `# Function to find centered``# tridecagonal number``def` `centeredTridecagonalNum(n) :``    ` `    ``# Formula to calculate nth``    ``# centered tridecagonal number``    ``return` `(``13` `*` `n ``*``           ``(n ``-` `1``) ``+` `2``) ``/``/` `2` `# Driver Code``if` `__name__ ``=``=` `'__main__'` `:``        ` `    ``n ``=` `3``    ``print``(centeredTridecagonalNum(n))``    ``n ``=` `10``    ``print``(centeredTridecagonalNum(n))``                ` `# This code is contributed``# by akt_mit`

## C#

 `// C# Program to find nth``// centered tridecagonal number``using` `System;` `class` `GFG``{` `// Function to find nth centered``// tridecagonal number``static` `long` `centeredTridecagonalNum(``long` `n)``{``    ``// Formula to calculate nth``    ``// centered tridecagonal number``    ``return` `(13 * n * (n - 1) + 2) / 2;``}` `// Driver Code``public` `static` `void` `Main ()``{``    ``long` `n = 3;``    ``Console.WriteLine(centeredTridecagonalNum(n));``    ``n = 10;``    ``Console.WriteLine(centeredTridecagonalNum(n));``}``}` `// This code is contributed by anuj_67.`

## PHP

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## Javascript

 ``
Output :
```40
586```

Time Complexity: O(1)
Auxiliary Space: O(1)

Reference: http://oeis.org/wiki/Figurate_numbers

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