C++ program to find Nth term of the series 1, 6, 18, 40, 75, ….

In this problem, we are given an integer N. Our task is to create a program to Find Nth term of series 1,6, 18, 40, 75 ...

Let’s take an example to understand the problem,

Input

N = 4

Output

40

Explanation

4^th term − (4 * 4 * 5 ) / 2 = 40

Solution Approach

A simple approach to solve the problem is by using the general formula for the nth term of the series. The formula for,

Nth term = ( N * N * (N + 1) ) / 2

Program to illustrate the working of our solution,

Example

 Live Demo

#include <iostream>
using namespace std;
int calcNthTerm(int N) {
   return ( (N*N*(N+1))/2 );
}
int main() {
   int N = 5;
   cout<<N<<"th term of the series is "<<calcNthTerm(N);
   return 0;
}

Output

5th term of the series is 75