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

Input: 9
Output: 191

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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:

 // CPP program to find N-th term of the series: // 9, 23, 45, 75, 113, 159......    #include 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 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 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# 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



Output:
11

Time Complexity: O(1)

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