Given a number **N**, the task is to find **N ^{th}** Triacontagon number.

An Triacontagon number is class of figurate number. It has 30 – sided polygon called triacontagon. The N-th triacontagonal number count’s the 30 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few triacontagonol numbers are

1, 30, 87, 172 …

**Examples:**

Input:N = 2Output:30Explanation:

The second triacontagonol number is 30.Input:N = 3Output:87

**Approach:** The N-th triacontagonal number is given by the formula:

- Nth term of s sided polygon =

- Therefore Nth term of 30 sided polygon is

Below is the implementation of the above approach:

## C++

`// C++ program for above approach` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Finding the nth triacontagonal number` `int` `triacontagonalNum(` `int` `n)` `{` ` ` `return` `(28 * n * n - 26 * n) / 2;` `}` `// Driver code` `int` `main()` `{` ` ` `int` `n = 3;` ` ` ` ` `cout << ` `"3rd triacontagonal Number is = "` ` ` `<< triacontagonalNum(n);` ` ` `return` `0;` `}` `// This code is contributed by shivanisinghss2110` |

## C

`// C program for above approach` `#include <stdio.h>` `#include <stdlib.h>` `// Finding the nth triacontagonal Number` `int` `triacontagonalNum(` `int` `n)` `{` ` ` `return` `(28 * n * n - 26 * n) / 2;` `}` `// Driver program to test above function` `int` `main()` `{` ` ` `int` `n = 3;` ` ` `printf` `(` `"3rd triacontagonal Number is = %d"` `,` ` ` `triacontagonalNum(n));` ` ` `return` `0;` `}` |

## Java

`// Java program for above approach` `import` `java.io.*;` `import` `java.util.*;` `class` `GFG {` ` ` `// Finding the nth triacontagonal number` `static` `int` `triacontagonalNum(` `int` `n)` `{` ` ` `return` `(` `28` `* n * n - ` `26` `* n) / ` `2` `;` `}` `// Driver code` `public` `static` `void` `main(String[] args)` `{` ` ` `int` `n = ` `3` `;` ` ` ` ` `System.out.println(` `"3rd triacontagonal Number is = "` `+` ` ` `triacontagonalNum(n));` `}` `}` `// This code is contributed by coder001` |

## Python3

`# Python3 program for above approach` `# Finding the nth triacontagonal Number` `def` `triacontagonalNum(n):` ` ` `return` `(` `28` `*` `n ` `*` `n ` `-` `26` `*` `n) ` `/` `/` `2` `# Driver Code` `n ` `=` `3` `print` `(` `"3rd triacontagonal Number is = "` `,` ` ` `triacontagonalNum(n))` `# This code is contributed by divyamohan123` |

## C#

`// C# program for above approach` `using` `System;` `class` `GFG{` ` ` `// Finding the nth triacontagonal number` `static` `int` `triacontagonalNum(` `int` `n)` `{` ` ` `return` `(28 * n * n - 26 * n) / 2;` `}` `// Driver code` `public` `static` `void` `Main()` `{` ` ` `int` `n = 3;` ` ` ` ` `Console.Write(` `"3rd triacontagonal Number is = "` `+` ` ` `triacontagonalNum(n));` `}` `}` `// This code is contributed by Akanksha_Rai` |

## Javascript

`<script>` `// JavaScript program for above approach` `// Finding the nth triacontagonal number` `function` `triacontagonalNum(n)` `{` ` ` `return` `(28 * n * n - 26 * n) / 2;` `}` `// Driver code` `var` `n = 3;` `document.write(` `"3rd triacontagonal Number is = "` `+ triacontagonalNum(n));` `</script>` |

**Output:**

3rd triacontagonal Number is = 87

**Reference:** https://en.wikipedia.org/wiki/Triacontagon

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