# Find Nth term of the series 2, 3, 10, 15, 26….

Given a number **N**, the task is to find the **Nth** term in series **2, 3, 10, 15, 26….****Example:**

Input:N = 2Output:3 2nd term = (2*2)-1 = 3Input:N = 5Output:26 5th term = (5*5)+1 = 26

**Approach:**

- Nth number of the series is obtained by
- Squaring the number itself.
- If the number is odd, add 1 to the squared number. And, subtract 1 if the number is even

- Since the starting number of the series is 2

1st term = 2

2nd term = (2 * 2) – 1 = 3

3rd term = (3 * 3) + 1 = 10

4th term = (4 * 4) – 1 = 15

5th term = (5 * 5) + 1 = 26

and so on….

- In general, Nth number is obtained by formula:

Below is the implementation of the above approach:

## C++

`// C++ program to find Nth term` `// of the series 2, 3, 10, 15, 26....` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to find Nth term` `int` `nthTerm(` `int` `N)` `{` ` ` `int` `nth = 0;` ` ` `// Nth term` ` ` `if` `(N % 2 == 1)` ` ` `nth = (N * N) + 1;` ` ` `else` ` ` `nth = (N * N) - 1;` ` ` `return` `nth;` `}` `// Driver Method` `int` `main()` `{` ` ` `int` `N = 5;` ` ` `cout << nthTerm(N) << endl;` ` ` `return` `0;` `}` |

## Java

`// Java program to find Nth term` `// of the series 2, 3, 10, 15, 26....` `class` `GFG` `{` `// Function to find Nth term` `static` `int` `nthTerm(` `int` `N)` `{` ` ` `int` `nth = ` `0` `;` ` ` `// Nth term` ` ` `if` `(N % ` `2` `== ` `1` `)` ` ` `nth = (N * N) + ` `1` `;` ` ` `else` ` ` `nth = (N * N) - ` `1` `;` ` ` `return` `nth;` `}` `// Driver code` `public` `static` `void` `main(String[] args)` `{` ` ` `int` `N = ` `5` `;` ` ` `System.out.print(nthTerm(N) +` `"\n"` `);` `}` `}` `// This code is contributed by Rajput-Ji` |

## Python3

`# Python3 program to find Nth term` `# of the series 2, 3, 10, 15, 26....` `# Function to find Nth term` `def` `nthTerm(N) :` ` ` `nth ` `=` `0` `;` ` ` `# Nth term` ` ` `if` `(N ` `%` `2` `=` `=` `1` `) :` ` ` `nth ` `=` `(N ` `*` `N) ` `+` `1` `;` ` ` `else` `:` ` ` `nth ` `=` `(N ` `*` `N) ` `-` `1` `;` ` ` `return` `nth;` `# Driver Method` `if` `__name__ ` `=` `=` `"__main__"` `:` ` ` `N ` `=` `5` `;` ` ` `print` `(nthTerm(N)) ;` `# This code is contributed by AnkitRai01` |

## C#

`// C# program to find Nth term` `// of the series 2, 3, 10, 15, 26....` `using` `System;` `class` `GFG` `{` `// Function to find Nth term` `static` `int` `nthTerm(` `int` `N)` `{` ` ` `int` `nth = 0;` ` ` `// Nth term` ` ` `if` `(N % 2 == 1)` ` ` `nth = (N * N) + 1;` ` ` `else` ` ` `nth = (N * N) - 1;` ` ` `return` `nth;` `}` `// Driver code` `public` `static` `void` `Main(String[] args)` `{` ` ` `int` `N = 5;` ` ` `Console.Write(nthTerm(N) +` `"\n"` `);` `}` `}` `// This code is contributed by PrinciRaj1992` |

## Javascript

`<script>` ` ` `// Javascript program to find Nth term` ` ` `// of the series 2, 3, 10, 15, 26....` ` ` ` ` `// Function to find Nth term` ` ` `function` `nthTerm(N)` ` ` `{` ` ` `let nth = 0;` ` ` `// Nth term ` ` ` `if` `(N % 2 == 1)` ` ` `nth = (N * N) + 1;` ` ` `else` ` ` `nth = (N * N) - 1;` ` ` `return` `nth;` ` ` `}` ` ` ` ` `let N = 5;` ` ` `document.write(nthTerm(N));` `// This code is contributed by divyeshrabadiya07.` `</script>` |

**Output:**

26

**Time Complexity:** O(1) since no loop is used the algorithm takes up constant time to perform the operations

**Auxiliary Space:** O(1) since no extra array is used so the space taken by the algorithm is constant