# Centered heptagonal number

Given a number n, the task is to find nth Centered heptagonal number.

Centered heptagonal number is centered figure number that represents a heptagon with dot in center and all other dot surrounding in heptagonal form. Nth centered heptagonal number can be calculated by using formula (7n2 – 7n + 2) / 2.

Examples :

```Input : n = 2
Output : 8

Input : n = 7
Output : 148
```

Please refer this diagram for pictorial representation.

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

Below is the implementation :

## C++

 `// CPP program to find n-th ` `// Centered heptagonal number ` `#include ` ` `  `using` `namespace` `std; ` ` `  `// Function to find Centered ` `// heptagonal number ` `int` `centered_heptagonal_num(``long` `int` `n) ` `{ ` `    ``// Formula to calculate nth ` `    ``// Centered heptagonal number ` `    ``return` `(7 * n * n - 7 * n + 2) / 2; ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``long` `int` `n = 5; ` `    ``cout << n << ``"th Centered heptagonal number : "``; ` `    ``cout << centered_heptagonal_num(n); ` `    ``return` `0; ` `} `

## Java

 `// Java program to find n-th Centered ` `// heptagonal number ` `import` `java.io.*; ` ` `  `class` `GFG { ` ` `  `    ``// Function to find Centered heptagonal ` `    ``// number ` `    ``static` `long` `centered_heptagonal_num(``long` `n) ` `    ``{ ` `         `  `        ``// Formula to calculate nth ` `        ``// Centered heptagonal number ` `        ``return` `(``7` `* n * n - ``7` `* n + ``2``) / ``2``; ` `    ``} ` `     `  `    ``// Driver Code ` `    ``public` `static` `void` `main (String[] args) ` `    ``{ ` `        ``long` `n = ``5``; ` `        ``System.out.println( n + ``"th Centered "` `                      ``+ ``"heptagonal number : "` `                ``+ centered_heptagonal_num(n)); ` `    ``} ` `} ` ` `  `// This code is contributed by anuj_67. `

## Python3

 `# Python program to find nth ` `# Centered heptagonal number ` ` `  `# Function to find Centered ` `# heptagonal number ` `def` `centered_heptagonal_num(n): ` ` `  `    ``# Formula to calculate nth ` `    ``# Centered heptagonal number ` `    ``return` `(``7` `*` `n ``*` `n ``-` `7` `*` `n ``+` `2``) ``/``/` `2` ` `  ` `  `# Driver Code ` `n ``=` `5` `print``(``"%sth Centered heptagonal number : "` `%``n, ` `                    ``centered_heptagonal_num(n)) `

## C#

 `//C# program to find n-th Centered ` `// heptagonal number ` `using` `System; ` ` `  `class` `GFG { ` ` `  `    ``// Function to find Centered heptagonal ` `    ``// number ` `    ``static` `long` `centered_heptagonal_num(``long` `n) ` `    ``{ ` `         `  `        ``// Formula to calculate nth ` `        ``// Centered heptagonal number ` `        ``return` `(7 * n * n - 7 * n + 2) / 2; ` `    ``} ` `     `  `    ``// Driver Code ` `    ``public` `static` `void` `Main () ` `    ``{ ` `        ``long` `n = 5; ` `        ``Console.WriteLine( n + ``"th Centered "` `                    ``+ ``"heptagonal number : "` `                ``+ centered_heptagonal_num(n)); ` `    ``} ` `} ` ` `  `// This code is contributed by anuj_67. `

## PHP

 ` `

Output :

`5th Centered heptagonal number : 71`

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.

My Personal Notes arrow_drop_up Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Improved By : jit_t, vt_m

Article Tags :

Be the First to upvote.

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.