Given an integer **N**, the task is to find the count of **0s** in an **N-level** hexagon.

**Examples:**

Input:N = 2Output:7Input:N = 3Output:19

**Approach:** For the values of **N = 1, 2, 3, …** it can be observed that a series will be formed as **1, 7, 19, 37, 61, 91, 127, 169, …**. It’s a difference series where differences are in AP as **6, 12, 18, …**.

Therefore the **N ^{th}** term of will be 1 + {6 + 12 + 18 +…..(n – 1) terms}

= 1 + (n – 1) * (2 * 6 + (n – 1 – 1) * 6) / 2

= 1 + (n – 1) * (12 + (n – 2) * 6) / 2

= 1 + (n – 1) * (12 + 6n – 12) / 2

= 1 + (n – 1) * (6n) / 2

**= 1 + (n – 1) * (3n)**

Below is the implementation of the above approach:

## C++

`// C++ implementation of the approach` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to return the count of` `// 0s in an n-level hexagon` `int` `count(` `int` `n)` `{` ` ` `return` `3 * n * (n - 1) + 1;` `}` `// Driver code` `int` `main()` `{` ` ` `int` `n = 3;` ` ` `cout << count(n);` ` ` `return` `0;` `}` |

## Java

`// Java implementation of the above approach` `class` `GFG` `{` ` ` ` ` `// Function to return the count of` ` ` `// 0s in an n-level hexagon` ` ` `static` `int` `count(` `int` `n)` ` ` `{` ` ` `return` `3` `* n * (n - ` `1` `) + ` `1` `;` ` ` `}` ` ` ` ` `// Driver code` ` ` `public` `static` `void` `main(String args[])` ` ` `{` ` ` `int` `n = ` `3` `;` ` ` ` ` `System.out.println(count(n));` ` ` `}` `}` `// This code is contributed by AnkitRai01` |

## Python3

`# Python3 implementation of the approach` `# Function to return the count of` `# 0s in an n-level hexagon` `def` `count(n):` ` ` `return` `3` `*` `n ` `*` `(n ` `-` `1` `) ` `+` `1` `# Driver code` `n ` `=` `3` `print` `(count(n))` `# This code is contributed by Mohit Kumar` |

## C#

`// C# implementation of the approach` `using` `System;` `class` `GFG` `{` ` ` `// Function to return the count of` `// 0s in an n-level hexagon` `static` `int` `count(` `int` `n)` `{` ` ` `return` `3 * n * (n - 1) + 1;` `}` `// Driver code` `static` `public` `void` `Main ()` `{` ` ` `int` `n = 3;` ` ` ` ` `Console.Write(count(n));` `}` `}` `// This code is contributed by ajit` |

## Javascript

`<script>` `// Javascript implementation of the approach` `// Function to return the count of` `// 0s in an n-level hexagon` `function` `count(n)` `{` ` ` `return` `3 * n * (n - 1) + 1;` `}` `// Driver code` `var` `n = 3;` `document.write(count(n));` `// This code is contributed by rutvik_56.` `</script>` |

**Output:**

19

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