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Find the Nth term of the series 4, 11, 30, 85, 248. . .

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Given a positive integer N. The task is to find Nth term of the series:

4, 11, 30, 85, 248…

Examples:

Input: N = 4
Output: 85

Input: N = 2
Output: 11

 

Approach:  

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

TN = 3N + N

Illustration:

Input: N = 4
Output: 85
Explanation: 
TN = 3N +N
     = 34 + 4
     = 81 +4
     = 85

Below is the implementation of the above problem:

C++




// C++ program to find N-th term
// of the series-
// 4, 11, 30, 85, 248...
#include <bits/stdc++.h>
using namespace std;
 
// Function to return Nth term
// of the series
int nthTerm(int N)
{
    return pow(3, N) + N;
}
 
// Driver Code
int main()
{
    // Get the value of N
    int N = 4;
    cout << nthTerm(N);
    return 0;
}


Java




// Java program to find N-th term
// of the series-
// 4, 11, 30, 85, 248...
class GFG
{
 
  // Function to return Nth term
  // of the series
  static int nthTerm(int N) {
    return (int)Math.pow(3, N) + N;
  }
 
  // Driver Code
  public static void main(String args[])
  {
 
    // Get the value of N
    int N = 4;
    System.out.println(nthTerm(N));
  }
}
 
// This code is contributed by saurabh_jaiswal.


Python3




# Python code for the above approach
 
# Function to return Nth term
# of the series
def nthTerm(N):
    return (3 ** N) + N;
 
# Driver Code
# Get the value of N
N = 4;
print(nthTerm(N));
 
# This code is contributed by Saurabh Jaiswal


C#




// C# program to find N-th term
// of the series-
// 4, 11, 30, 85, 248...
using System;
class GFG
{
 
  // Function to return Nth term
  // of the series
  static int nthTerm(int N) {
    return (int)Math.Pow(3, N) + N;
  }
 
  // Driver Code
  public static void Main()
  {
 
    // Get the value of N
    int N = 4;
    Console.Write(nthTerm(N));
  }
}
 
// This code is contributed by Samim Hossain Mondal.


Javascript




<script>
      // JavaScript code for the above approach
 
      // Function to return Nth term
      // of the series
      function nthTerm(N) {
          return Math.pow(3, N) + N;
      }
 
      // Driver Code
 
      // Get the value of N
      let N = 4;
      document.write(nthTerm(N));
 
// This code is contributed by Potta Lokesh
  </script>


 
 

Output

85

 Time Complexity: O(log3N)

Auxiliary Space: O(1), since no extra space has been taken.



Last Updated : 13 Jul, 2022
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