Program to find the Nth number of the series 2, 10, 24, 44, 70…..

Given a number N, the task is to find the Nth (N may be up to 10^18) term of this series:

2, 10, 24, 44, 70…..

The answer can be very large so print answer under modulo 10^9+9.**Examples:**

Input: N = 2 Output: 10 Input: N = 5 Output: 70

**Approach:**The formula for Nth term will be:

Nth term = 3*n*n – n

Below is the implementation of the above approach:

## C++

`// CPP program to find` `// the Nth term of the series` `// 2, 10, 24, 44, 70.....` `#include <bits/stdc++.h>` `using` `namespace` `std;` `#define mod 1000000009` `// function to return nth term of the series` `int` `NthTerm(` `long` `long` `n)` `{` ` ` `long` `long` `x = (3 * n * n) % mod;` ` ` `return` `(x - n + mod) % mod;` `}` `// Driver code` `int` `main()` `{` `// Get N` ` ` `long` `long` `N = 4;` ` ` `// Get Nth term` ` ` `cout << NthTerm(N);` ` ` `return` `0;` `}` |

## Java

`// Java program to find N-th` `// term of the series:` `import` `java.util.*;` `import` `java.lang.*;` `import` `java.io.*;` `class` `GFG {` ` ` `// function to return nth term of the series` ` ` `static` `long` `NthTerm(` `long` `n)` ` ` `{` ` ` `long` `x = (` `3` `* n * n) % ` `1000000009` `;` ` ` `return` `(x - n + ` `1000000009` `) % ` `1000000009` `;` ` ` `}` ` ` `// Driver Code` ` ` `public` `static` `void` `main(String args[])` ` ` `{` ` ` `// Taking n as 4` ` ` `long` `N = ` `4` `;` ` ` `// Printing the nth term` ` ` `System.out.println(NthTerm(N));` ` ` `}` `}` |

## Python3

`# Python 3 program to find ` `# N-th term of the series: ` ` ` ` ` `# Function for calculating ` `# Nth term of series ` `def` `NthTerm(N) : ` ` ` ` ` `# return nth term` ` ` `x ` `=` `(` `3` `*` `N` `*` `N)` `%` `1000000009` ` ` `return` `((x ` `-` `N ` `+` `1000000009` `)` `%` `1000000009` `) ` ` ` `# Driver code ` `if` `__name__ ` `=` `=` `"__main__"` `: ` ` ` ` ` `N ` `=` `4` ` ` ` ` `# Function Calling ` ` ` `print` `(NthTerm(N))` |

## C#

`// C# program to find N-th` `// term of the series:` `using` `System;` `class` `GFG` `{` `// function to return nth` `// term of the series` `static` `long` `NthTerm(` `long` `n)` `{` ` ` `long` `x = (3 * n * n) % 1000000009;` ` ` `return` `(x - n + 1000000009) % 1000000009;` `}` `// Driver Code` `public` `static` `void` `Main()` `{` ` ` `// Taking n as 4` ` ` `long` `N = 4;` ` ` `// Printing the nth term` ` ` `Console.Write(NthTerm(N));` `}` `}` `// This code is contributed` `// by ChitraNayal` |

## PHP

`<?php` `// PHP program to find` `// the Nth term of the series` `// 2, 10, 24, 44, 70.....` `// function to return Nth` `// term of the series` `function` `NthTerm(` `$n` `)` `{` ` ` `$mod` `= 1000000009;` ` ` ` ` `$x` `= (3 * ` `$n` `* ` `$n` `) % ` `$mod` `;` ` ` `return` `(` `$x` `- ` `$n` `+ ` `$mod` `) % ` `$mod` `;` `}` `// Driver code` `$N` `= 4;` `// Get Nth term` `echo` `NthTerm(` `$N` `);` `// This code is contributed` `// by Mahadev99` `?>` |

## Javascript

`<script>` `// Javascript program to find N-th` `// term of the series:` ` ` `// function to return nth term of the series` ` ` `function` `NthTerm( n) {` ` ` `let x = (3 * n * n) % 1000000009;` ` ` `return` `(x - n + 1000000009) % 1000000009;` ` ` `}` ` ` `// Driver Code` ` ` ` ` `// Taking n as 4` ` ` `let N = 4;` ` ` `// Prleting the nth term` ` ` `document.write(NthTerm(N));` `// This code contributed by Princi Singh` `</script>` |

**Output:**

44

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