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Triacontagon Number
• Last Updated : 16 Mar, 2021

Given a number N, the task is to find Nth 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 = 2
Output: 30
Explanation:
The second triacontagonol number is 30.
Input: N = 3
Output: 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 using namespace std; // Finding the nth triacontagonal numberint triacontagonalNum(int n){    return (28 * n * n - 26 * n) / 2;} // Driver codeint 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 #include  // Finding the nth triacontagonal Numberint triacontagonalNum(int n){    return (28 * n * n - 26 * n) / 2;} // Driver program to test above functionint main(){    int n = 3;    printf("3rd triacontagonal Number is = %d",           triacontagonalNum(n));     return 0;}

## Java

 // Java program for above approachimport java.io.*;import java.util.*; class GFG {     // Finding the nth triacontagonal numberstatic int triacontagonalNum(int n){    return (28 * n * n - 26 * n) / 2;} // Driver codepublic 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 Numberdef triacontagonalNum(n):     return (28 * n * n - 26 * n) // 2 # Driver Coden = 3print("3rd triacontagonal Number is = ",                   triacontagonalNum(n)) # This code is contributed by divyamohan123

## C#

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

## Javascript

 
Output:
3rd triacontagonal Number is = 87

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