# Program to check if N is a Centered Tridecagonal Number

Given a number **N**, the task is to check if **N** is a Centered Tridecagonal Number or not. If the number **N** is a Centered Tridecagonal Number then print **“Yes”** else print **“No”**.

Centered tridecagonal numberrepresents a dot at the center and other dots surrounding the center dot in the successive tridecagonal(13 sided polygon) layer. The first few Centered tridecagonal numbers are1, 14, 40, 79 …

**Examples:**

Input:N = 14Output:YesExplanation:

Second Centered tridecagonal number is 14.

Input:N = 30Output:No

**Approach:**

1. The **K ^{th}** term of the Centered Tridecagonal Number is given as

2. As we have to check that the given number can be expressed as a Centered Tridecagonal Number or not. This can be checked as follows:

=>

=>

3. If the value of **K** calculated using the above formula is an integer, then **N** is a Centered Tridecagonal Number.

4. Else the number **N** is not a Centered Tridecagonal Number.

Below is the implementation of the above approach:

## C++

`// C++ program for the above approach` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to check if the number N` `// is a Centered tridecagonal number` `bool` `isCenteredtridecagonal(` `int` `N)` `{` ` ` `float` `n` ` ` `= (13 + ` `sqrt` `(104 * N + 65))` ` ` `/ 26;` ` ` `// Condition to check if the N` ` ` `// is a Centered tridecagonal number` ` ` `return` `(n - (` `int` `)n) == 0;` `}` `// Driver Code` `int` `main()` `{` ` ` `// Given Number` ` ` `int` `N = 14;` ` ` `// Function call` ` ` `if` `(isCenteredtridecagonal(N)) {` ` ` `cout << ` `"Yes"` `;` ` ` `}` ` ` `else` `{` ` ` `cout << ` `"No"` `;` ` ` `}` ` ` `return` `0;` `}` |

## Java

`// Java program for the above approach` `class` `GFG{` `// Function to check if the number N` `// is a centered tridecagonal number` `static` `boolean` `isCenteredtridecagonal(` `int` `N)` `{` ` ` `float` `n = (` `float` `) ((` `13` `+ Math.sqrt(` `104` `* N +` ` ` `65` `)) / ` `26` `);` ` ` `// Condition to check if the N` ` ` `// is a centered tridecagonal number` ` ` `return` `(n - (` `int` `)n) == ` `0` `;` `}` `// Driver Code` `public` `static` `void` `main(String[] args)` `{` ` ` ` ` `// Given Number` ` ` `int` `N = ` `14` `;` ` ` `// Function call` ` ` `if` `(isCenteredtridecagonal(N))` ` ` `{` ` ` `System.out.print(` `"Yes"` `);` ` ` `}` ` ` `else` ` ` `{` ` ` `System.out.print(` `"No"` `);` ` ` `}` `}` `}` `// This code is contributed by sapnasingh4991` |

## Python3

`# Python3 program for the above approach` `import` `numpy as np` `# Function to check if the number N` `# is a centered tridecagonal number` `def` `isCenteredtridecagonal(N):` ` ` `n ` `=` `(` `13` `+` `np.sqrt(` `104` `*` `N ` `+` `65` `)) ` `/` `26` ` ` `# Condition to check if N` ` ` `# is centered tridecagonal number` ` ` `return` `(n ` `-` `int` `(n)) ` `=` `=` `0` `# Driver Code` `N ` `=` `14` `# Function call` `if` `(isCenteredtridecagonal(N)):` ` ` `print` `(` `"Yes"` `)` `else` `:` ` ` `print` `(` `"No"` `)` `# This code is contributed by PratikBasu` |

## C#

`// C# program for the above approach` `using` `System;` `class` `GFG{` `// Function to check if the number N` `// is a centered tridecagonal number` `static` `bool` `isCenteredtridecagonal(` `int` `N)` `{` ` ` `float` `n = (` `float` `) ((13 + Math.Sqrt(104 * N +` ` ` `65)) / 26);` ` ` `// Condition to check if the N` ` ` `// is a centered tridecagonal number` ` ` `return` `(n - (` `int` `)n) == 0;` `}` `// Driver Code` `public` `static` `void` `Main(` `string` `[] args)` `{` ` ` ` ` `// Given Number` ` ` `int` `N = 14;` ` ` `// Function call` ` ` `if` `(isCenteredtridecagonal(N))` ` ` `{` ` ` `Console.Write(` `"Yes"` `);` ` ` `}` ` ` `else` ` ` `{` ` ` `Console.Write(` `"No"` `);` ` ` `}` `}` `}` `// This code is contributed by rutvik_56` |

## Javascript

`<script>` `// Javascript program for the above approach` `// Function to check if the number N` `// is a Centered tridecagonal number` `function` `isCenteredtridecagonal(N)` `{` ` ` `let n` ` ` `= (13 + Math.sqrt(104 * N + 65))` ` ` `/ 26;` ` ` `// Condition to check if the N` ` ` `// is a Centered tridecagonal number` ` ` `return` `(n - parseInt(n)) == 0;` `}` `// Driver Code` `// Given Number` `let N = 14;` `// Function call` `if` `(isCenteredtridecagonal(N)) {` ` ` `document.write(` `"Yes"` `);` `}` `else` `{` ` ` `document.write(` `"No"` `);` `}` `// This code is contributed by subham348.` `</script>` |

**Output:**

Yes

**Time Complexity: **O(1)

**Auxiliary Space: **O(1)

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