Given a number N. The task is to write a program to find the Nth term in the below series:
0, 2, 4, 8, 12, 18…
Examples:
Input: 3 Output: 4 For N = 3 Nth term = ( 3 + ( 3 - 1 ) * 3 ) / 2 = 4 Input: 5 Output: 12
On observing carefully, the Nth term in the above series can be generalized as:
Nth term = ( N + ( N - 1 ) * N ) / 2
Below is the implementation of the above approach:
C++
// CPP program to find N-th term of the series: // 0, 2, 4, 8, 12, 18... #include <iostream> using namespace std; // Calculate Nth term of series int nthTerm( int N) { return (N + N * (N - 1)) / 2; } // Driver Function int main() { int N = 5; cout << nthTerm(N); return 0; } |
Java
// Java program to find N-th term of the series: // 0, 2, 4, 8, 12, 18... import java.io.*; // Main class for main method class GFG { public static int nthTerm( int N) { // By using above formula return (N + (N - 1 ) * N) / 2 ; } // Driver code public static void main(String[] args) { int N = 5 ; // 5th term is 12 System.out.println(nthTerm(N)); } } |
Python 3
# Python 3 program to find N-th term of the series: # 0, 2, 4, 8, 12, 18. # Calculate Nth term of series def nthTerm(N) : return (N + N * (N - 1 )) / / 2 # Driver Code if __name__ = = "__main__" : N = 5 print (nthTerm(N)) # This code is contributed by ANKITRAI1 |
C#
// C# program to find N-th term of the series: // 0, 2, 4, 8, 12, 18... using System; class gfg { // Calculate Nth term of series public int nthTerm( int N) { int n = ((N + N * (N - 1)) / 2); return n; } //Driver program static void Main( string [] args) { gfg p = new gfg(); int a = p.nthTerm(5); Console.WriteLine(a); Console.Read(); } } //This code is contributed by SoumikMondal |
PHP
<?php // PHP program to find // N-th term of the series: // 0, 2, 4, 8, 12, 18... // Calculate Nth term of series function nthTerm( $N ) { return (int)(( $N + $N * ( $N - 1)) / 2); } // Driver Code $N = 5; echo nthTerm( $N ); // This code is contributed by mits ?> |
Javascript
<script> // JavaScript program to find N-th term of the series: // 0, 2, 4, 8, 12, 18... // Calculate Nth term of series function nthTerm(N) { return parseInt((N + N * (N - 1)) / 2); } // Driver Function let N = 5; document.write(nthTerm(N)); // This code contributed by Rajput-Ji </script> |
Output:
12
Time Complexity: O(1)
Auxiliary space: O(1) as it is using constant variables
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