Program to find the Nth term of series -1, 2, 11, 26, 47……

Given a number N, the task is to find the Nth term of this series:

-1, 2, 11, 26, 47, 74, .....

**Examples:**

Input:3Output:11Explanation:when N = 3 Nth term = ( (3 * N * N) - (6 * N) + 2 ) = ( (3 * 3 * 3) - (6 * 3) + 2 ) = 11Input:9Output:191

**Approach:**

The Nth term of the given series can be generalised as:

Nth term of the series : ( (3 * N * N) - (6 * N) + 2 )

Below is the implementation of the above problem:**Program:**

## C++

`// CPP program to find N-th term of the series: ` `// 9, 23, 45, 75, 113, 159...... ` ` ` `#include <iostream>;` `using` `namespace` `std; ` `// calculate Nth term of series ` `int` `nthTerm(` `int` `N) ` `{ ` ` ` `return` `((3 * N * N) - (6 * N) + 2); ` `} ` ` ` `// Driver Function ` `int` `main() ` `{ ` ` ` ` ` `// Get the value of N ` ` ` `int` `N = 3; ` ` ` ` ` `// Find the Nth term ` ` ` `// and print it ` ` ` `cout << nthTerm(N); ` ` ` ` ` `return` `0; ` `}` |

## Java

`// Java program to find N-th term of the series:` `// 9, 23, 45, 75, 113, 159......` ` ` `class` `GFG {` ` ` ` ` `// calculate Nth term of series` ` ` `static` `int` `nthTerm(` `int` `N)` ` ` `{` ` ` `return` `((` `3` `* N * N) - (` `6` `* N) + ` `2` `);` ` ` `}` ` ` ` ` `// Driver code` ` ` `public` `static` `void` `main(String[] args) {` ` ` `int` `N = ` `3` `;` ` ` ` ` `// Find the Nth term` ` ` `// and print it` ` ` `System.out.println(nthTerm(N));` ` ` `}` `}` `// This code is contributed by bilal-hungund` |

## Python3

`# Python3 program to find N-th term` `# of the series:` `# 9, 23, 45, 75, 113, 159......` `def` `nthTerm(N):` ` ` ` ` `#calculate Nth term of series` ` ` `return` `((` `3` `*` `N ` `*` `N) ` `-` `(` `6` `*` `N) ` `+` `2` `);` `# Driver Code` `if` `__name__` `=` `=` `'__main__'` `:` ` ` `n ` `=` `3` ` ` `#Find the Nth term` ` ` `# and print it` ` ` `print` `(nthTerm(n))` `# this code is contributed by bilal-hungund` |

## C#

`// C# program to find N-th term of the series:` `// 9, 23, 45, 75, 113, 159......` `using` `System;` `class` `GFG` `{` `// calculate Nth term of series` `static` `int` `nthTerm(` `int` `N)` `{` ` ` `return` `((3 * N * N) - (6 * N) + 2);` `}` `// Driver code` `public` `static` `void` `Main()` `{` ` ` `int` `N = 3;` ` ` ` ` `// Find the Nth term` ` ` `// and print it` ` ` `Console.WriteLine(nthTerm(N));` `}` `}` `// This code is contributed by inder_verma` |

## PHP

`<?php` `// PHP program to find N-th term of` `// the series: 9, 23, 45, 75, 113, 159......` `// calculate Nth term of series` `function` `nthTerm(` `$N` `)` `{` ` ` `return` `((3 * ` `$N` `* ` `$N` `) -` ` ` `(6 * ` `$N` `) + 2);` `}` `// Driver Code` `// Get the value of N` `$N` `= 3;` `// Find the Nth term` `// and print it` `echo` `nthTerm(` `$N` `);` `// This code is contributed by Raj` `?>` |

## Javascript

`<script>` `// JavaScript program to find N-th term of the series:` `// 9, 23, 45, 75, 113, 159......` ` ` ` ` ` ` `// calculate Nth term of series` ` ` `function` `nthTerm(N)` ` ` `{` ` ` `return` `((3 * N * N) - (6 * N) + 2);` ` ` `}` ` ` ` ` `// Driver Function` ` ` `// Get the value of N` ` ` `let N = 3;` ` ` ` ` `// Find the Nth term` ` ` `// and print it` ` ` `document.write(nthTerm(N)); ` ` ` `// This code is contributed by Surbhi Tyagi` `</script>` |

**Output:**

11

**Time Complexity:** O(1)

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