# Centered Dodecagonal Number

Given a number n, find the nth Centered Dodecagonal Number.
The Centered Dodecagonal Number represents a dot in the center and other dots surrounding it in successive dodecagonal(12 sided polygon) layers.

Examples :

```Input :  3
Output : 37

Input : 7
Output :253
```

The first few centered dodecagonal numbers are:
1, 13, 37, 73, 121, 181, 253, 337, 433, 541, 661…………………..

The formula for the nth Centered dodecagonal number:

```
```

## C++

 `// C++ Program to find ` `// nth centered ` `// Dodecagonal number ` `#include ` `using` `namespace` `std; ` ` `  `// Function to calculate Centered ` `// Dodecagonal number ` `int` `centeredDodecagonal(``long` `int` `n) ` `{ ` `    ``// Formula to calculate nth ` `    ``// centered Dodecagonal number ` `    ``return` `6 * n * (n - 1) + 1; ` `} ` ` `  `// Drivers Code ` `int` `main() ` `{ ` `    ``long` `int` `n = 2; ` `    ``cout << centeredDodecagonal(n); ` `    ``cout << endl; ` `    ``n = 9; ` `    ``cout << centeredDodecagonal(n); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java Program to find ` `// nth centered ` `// Dodecagonal number ` `import` `java.io.*; ` ` `  `class` `GFG  ` `{ ` `// Function to calculate  ` `// Centered Dodecagonal number ` `static` `long` `centeredDodecagonal(``long` `n) ` `{ ` `    ``// Formula to calculate nth ` `    ``// centered Dodecagonal number ` `    ``return` `6` `* n * (n - ``1``) + ``1``; ` `} ` ` `  `// Driver Code ` `public` `static` `void` `main (String[] args)  ` `{ ` `    ``long` `n = ``2``; ` `    ``System.out.println(centeredDodecagonal(n)); ` ` `  `    ``n = ``9``; ` `    ``System.out.println(centeredDodecagonal(n)); ` `} ` `} ` ` `  `// This code is contributed by anuj_67. `

Output :

```13
433
```

References
http://oeis.org/A003154

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