Related Articles

# Second hexagonal numbers

• Last Updated : 13 Jul, 2021

The Second hexagonal numbers series can be represented as

3, 10, 21, 36, 55, 78, 105, 136, 171, 210, 253, …..

Nth term

Given an integer N. The task is to find the N-th term of the given series.
Examples

Input: N = 1
Output: 3
Input: N = 4
Output: 36

Approach: The idea is to find the general term for the Second hexagonal numbers. Below is the computation of the general term for second hexagonal numbers:

1st Term = 1 * (2*1 + 1) = 3
2nd term = 2 * (2*2 + 1) = 10
3rd term = 3 * (2*3 + 1) = 21
4th term = 4 * (2*4 + 1) = 36

Nth term = n * (2*n + 1)
Therefore, the Nth term of the series is given as Below is the implementation of above approach:

## C++

 `// C++ implementation to``// find N-th term``// in the series``#include ``#include ``using` `namespace` `std;` `// Function to find N-th term``// in the series``void` `findNthTerm(``int` `n)``{``    ``cout << n * (2 * n + 1) << endl;``}` `// Driver code``int` `main()``{``    ``int` `N = 4;``    ``findNthTerm(N);` `    ``return` `0;``}`

## Java

 `// Java implementation to``// find N-th term``// in the series``class` `GFG{``    ` `// Function to find N-th term``// in the series``static` `void` `findNthTerm(``int` `n)``{``    ``System.out.print(n * (``2` `* n + ``1``));``}` `// Driver code``public` `static` `void` `main (String[] args)``{``    ``int` `N = ``4``;``    ``findNthTerm(N);``}``}` `// This code is contributed by Ritik Bansal`

## Python3

 `# Python3 implementation to``# find N-th term``# in the series` `# Function to find N-th term``# in the series``def` `findNthTerm(n):``    ``print``(n ``*` `(``2` `*` `n ``+` `1``))` `# Driver code``N ``=` `4` `# Function call``findNthTerm(N)` `# This code is contributed by Vishal Maurya`

## C#

 `// C# implementation to``// find N-th term``// in the series``using` `System;``class` `GFG{``    ` `// Function to find N-th term``// in the series``static` `void` `findNthTerm(``int` `n)``{``    ``Console.Write(n * (2 * n + 1));``}` `// Driver code``public` `static` `void` `Main()``{``    ``int` `N = 4;``    ``findNthTerm(N);``}``}` `// This code is contributed by Code_Mech`

## Javascript

 ``
Output:
36

Time Complexity: O(1)
Auxiliary Space: O(1)

Reference:OEIS

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.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

My Personal Notes arrow_drop_up