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Find n-th term in the series 7, 15, 32, …
• Difficulty Level : Basic
• Last Updated : 20 Apr, 2021

Given a series 7, 15, 32, …… Find the nth term of this series.
Examples :

```Input : 5
Output : 138

Input : 7
Output : 568```

Approach : By seeing the pattern of the series we can easily identify that it is a mixed series.
S = 7, 15, 32…..
Each element in the series is multiplied by 2 and then incremented one more than the previous.
S = 7, 15 (2 * 7 + 1), 32 (2 * 15 + 2)…….
By using iteration we can easily find nth term of the series.
Below is the implementation of the above approach :

## C++

 `// CPP program to find nth term``#include ``using` `namespace` `std;` `// utility function``int` `findTerm(``int` `n)``{``    ``if` `(n == 1)``        ``return` `n;` `    ``else` `{` `        ``// since first element of the``        ``// series is 7, we initailise``        ``// a variable with 7``        ``int` `term = 7;` `        ``// Using iteration to find nth``        ``// term``        ``for` `(``int` `i = 2; i <= n; i++)``            ``term = term * 2 + (i - 1);       ` `        ``return` `term;``    ``}``}` `// driver function``int` `main()``{``    ``int` `n = 5;``    ``cout << findTerm(n);``    ``return` `0;``}`

## Java

 `// Java program to find nth term``import` `java.lang.*;` `class` `GFG {``    ` `// utility function``static` `int` `findTerm(``int` `n)``{``    ``if` `(n == ``1``)``    ``return` `n;` `    ``else` `{` `    ``// since first element of the``    ``// series is 7, we initailise``    ``// a variable with 7``    ``int` `term = ``7``;` `    ``// Using iteration to find nth``    ``// term``    ``for` `(``int` `i = ``2``; i <= n; i++)``        ``term = term * ``2` `+ (i - ``1``);` `    ``return` `term;``    ``}``}` `// Driver code``public` `static` `void` `main(String[] args)``{``    ``int` `n = ``5``;``    ``System.out.print(findTerm(n));``}``}` `// This code is contributed by Anant Agarwal.`

## Python3

 `# Python3 program to find nth term` `# utility function``def` `findTerm(n) :` `    ``if` `n ``=``=` `1` `:``        ``return` `n``    ``else` `:``        ` `        ``# since first element of the``        ``# series is 7, we initailise``        ``# a variable with 7``        ``term ``=` `7` `        ``# Using iteration to find nth``        ``# term``        ``for` `i ``in` `range``(``2``, n ``+` `1``) :``            ``term ``=` `term ``*` `2` `+` `(i ``-` `1``);    ` `    ``return` `term;` `# driver function``print` `(findTerm(``5``))` `# This code is contributed by Saloni Gupta`

## C#

 `// C# program to find nth term``using` `System;` `class` `GFG {` `    ``// utility function``    ``static` `int` `findTerm(``int` `n)``    ``{``        ``if` `(n == 1)``            ``return` `n;` `        ``else` `{` `            ``// since first element of the``            ``// series is 7, we initailise``            ``// a variable with 7``            ``int` `term = 7;` `            ``// Using iteration to find nth``            ``// term``            ``for` `(``int` `i = 2; i <= n; i++)``                ``term = term * 2 + (i - 1);` `            ``return` `term;``        ``}``    ``}` `    ``// Driver code``    ``public` `static` `void` `Main()``    ``{``        ``int` `n = 5;``        ``Console.WriteLine(findTerm(n));``    ``}``}` `// This code is contributed by vt_m.`

## PHP

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## Javascript

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Output :

`138`

This article is contributed by Saloni Gupta . If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
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