Given a series 7, 15, 32, …… Find the nth term of this series.
Examples :
Input : 5 Output : 138 Input : 7 Output : 568
Approach: By seeing the pattern of the series we can easily identify that it is a mixed series.
S = 7, 15, 32…..
Each element in the series is multiplied by 2 and then incremented one more than the previous.
S = 7, 15 (2 * 7 + 1), 32 (2 * 15 + 2)…….
By using iteration we can easily find nth term of the series.
Below is the implementation of the above approach :
C++
// CPP program to find nth term #include <bits/stdc++.h> using namespace std; // utility function int findTerm(int n) { if (n == 1) return n; else { // since first element of the // series is 7, we initialise // a variable with 7 int term = 7; // Using iteration to find nth // term for (int i = 2; i <= n; i++) term = term * 2 + (i - 1); return term; } } // driver function int main() { int n = 5; cout << findTerm(n); return 0; } |
Java
// Java program to find nth term import java.lang.*; class GFG { // utility function static int findTerm(int n) { if (n == 1) return n; else { // since first element of the // series is 7, we initialise // a variable with 7 int term = 7; // Using iteration to find nth // term for (int i = 2; i <= n; i++) term = term * 2 + (i - 1); return term; } } // Driver code public static void main(String[] args) { int n = 5; System.out.print(findTerm(n)); } } // This code is contributed by Anant Agarwal. |
Python3
# Python3 program to find nth term # utility function def findTerm(n) : if n == 1 : return n else : # since first element of the # series is 7, we initialise # a variable with 7 term = 7 # Using iteration to find nth # term for i in range(2, n + 1) : term = term * 2 + (i - 1); return term; # driver function print (findTerm(5)) # This code is contributed by Saloni Gupta |
C#
// C# program to find nth term using System; class GFG { // utility function static int findTerm(int n) { if (n == 1) return n; else { // since first element of the // series is 7, we initialise // a variable with 7 int term = 7; // Using iteration to find nth // term for (int i = 2; i <= n; i++) term = term * 2 + (i - 1); return term; } } // Driver code public static void Main() { int n = 5; Console.WriteLine(findTerm(n)); } } // This code is contributed by vt_m. |
PHP
<?php // PHP program to find nth term // utility function function findTerm($n) { if ($n == 1) return $n; else { // since first element of the // series is 7, we initialise // a variable with 7 $term = 7; // Using iteration to find nth // term for ($i = 2; $i <= $n; $i++) $term = $term * 2 + ($i - 1); return $term; } } // Driver Code $n = 5; echo(findTerm($n)); // This code is contributed by Ajit. ?> |
Javascript
<script> // Javascript program to find nth term // utility function function findTerm(n) { if (n == 1) return n; else { // since first element of the // series is 7, we initialise // a variable with 7 let term = 7; // Using iteration to find nth // term for (let i = 2; i <= n; i++) term = term * 2 + (i - 1); return term; } } // Driver Code let n = 5; document.write(findTerm(n)); // This code is contributed by gfgking. </script> |
138
Time Complexity: O(n) since for loop will run for n times in worst case
Auxiliary Space: O(1)
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