Given a number N, the task is to find the Nth term in series 12, 35, 81, 173, 357, …
Example:
Input: N = 2
Output: 35
2nd term = (12*2) + 11
= 35
Input: N = 5
Output: 357
5th term = (12*(2^4))+11*((2^4)-1)
= 357
Approach:
- Each and every number is obtained by multiplying the previous number by 2 and the addition of 11 to it.
- Since starting number is 12.
1st term = 12 2nd term = (12 * 2) / 11 = 35 3rd term = (35 * 2) / 11 = 81 4th term = (81 * 2) / 11 = 173 And, so on....
- In general, Nth number is obtained by formula:
Below is the implementation of the above approach:
C++
// C++ program to find the Nth term// in series 12, 35, 81, 173, 357, ...#include <bits/stdc++.h>using namespace std;// Function to find Nth termint nthTerm(int N){ int nth = 0, first_term = 12; // Nth term nth = (first_term * (pow(2, N - 1))) + 11 * ((pow(2, N - 1)) - 1); return nth;}// Driver Methodint main(){ int N = 5; cout << nthTerm(N) << endl; return 0;} |
Java
// Java program to find the Nth term// in series 12, 35, 81, 173, 357, ...class GFG{// Function to find Nth termstatic int nthTerm(int N){ int nth = 0, first_term = 12; // Nth term nth = (int) ((first_term * (Math.pow(2, N - 1))) + 11 * ((Math.pow(2, N - 1)) - 1)); return nth;}// Driver codepublic 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 the Nth term # in series 12, 35, 81, 173, 357, ... # Function to find Nth term def nthTerm(N) : nth = 0; first_term = 12; # Nth term nth = (first_term * (pow(2, N - 1))) + \ 11 * ((pow(2, N - 1)) - 1); return nth; # Driver Method if __name__ == "__main__" : N = 5; print(nthTerm(N)) ; # This code is contributed by AnkitRai01 |
C#
// C# program to find the Nth term// in series 12, 35, 81, 173, 357, ...using System;class GFG{// Function to find Nth termstatic int nthTerm(int N){ int nth = 0, first_term = 12; // Nth term nth = (int) ((first_term * (Math.Pow(2, N - 1))) + 11 * ((Math.Pow(2, N - 1)) - 1)); return nth;}// Driver codepublic 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 the Nth term // in series 12, 35, 81, 173, 357, ... // Function to find Nth term function nthTerm(N) { let nth = 0, first_term = 12; // Nth term nth = (first_term * (Math.pow(2, N - 1))) + 11 * ((Math.pow(2, N - 1)) - 1); return nth; } let N = 5; document.write(nthTerm(N)); // This code is contributed by divyeshrabadiya07.</script> |
Output:
357
Time complexity: O(log N) for given input N because using inbuilt pow function
Auxiliary Space: O(1)
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