Given a number n, the task is to find the n-th term in series 1, 6, 18, 40, 75, …
Example:
Input: N = 2
Output: 6
Explanation:
2nd term = (2^2*(2+1))/2
= 6
Input: N = 5
Output: 75
Explanation:
5th term = (5^2*(5+1))/2
= 75
Approach:
Nth term = (N^2*(N+1))/2
Implementation of the above approach is given below:
C++
// CPP code to generate// 'Nth' term of this sequence#include <bits/stdc++.h>using namespace std;// Function to generate a fixed numberint nthTerm(int N){ int nth = 0; //(N^2*(N+1))/2 nth = (N * N * (N + 1)) / 2; return nth;}// Driver Methodint main(){ int N = 5; cout << nthTerm(N) << endl; return 0;} |
Java
// Java code to generate// 'Nth' term of this sequenceclass GFG { // Function to generate a fixed number public static int nthTerm(int N) { int nth = 0; //(N^2*(N+1))/2 nth = (N * N * (N + 1)) / 2; return nth; } // Driver Method public static void main(String[] args) { int N = 5; System.out.println(nthTerm(N)); } // This code is contributed by 29AjayKumar} |
Python3
# python program to find out'Nth' term of this sequence # Function to generate a fixed numberdef nthTerm(N): nth = 0 nth = (N * N * (N + 1))//2 return nth# Driver codeN = 5print(nthTerm(N))# This code is contributed by Shrikant13 |
C#
// C# code to generate// 'Nth' term of this sequenceusing System;public class GFG { // Function to generate a fixed number public static int nthTerm(int N) { int nth = 0; //(N^2*(N+1))/2 nth = (N * N * (N + 1)) / 2; return nth; } // Driver Method public static void Main(string[] args) { int N = 5; Console.WriteLine(nthTerm(N)); }}// This code is contributed by Shrikant13 |
PHP
<?php// PHP code to generate// 'Nth' term of this sequence// Function to generate a fixed numberfunction nthTerm($N){ $nth = 0; // (N^2*(N+1))/2 $nth = ($N * $N * ($N + 1)) / 2; return $nth;}// Driver Code$N = 5;echo nthTerm($N);// This code is contributed// by chandan_jnu?> |
Javascript
<script>// Javascript code to generate// 'Nth' term of this sequence// Function to generate a fixed numberfunction nthTerm(N){ let nth = 0; //(N^2*(N+1))/2 nth = parseInt((N * N * (N + 1)) / 2); return nth;}// Driver Methodlet N = 5;document.write(nthTerm(N));// This code is contributed by subham348.</script> |
Output:
75
Time Complexity: O(1)
Auxiliary Space: O(1), since no extra space has been taken.
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