# Centered tridecagonal number

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

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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



Output :

40
586

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

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