Find Nth term of the series 1, 8, 54, 384…

• Difficulty Level : Medium
• Last Updated : 15 Mar, 2021

Given a number N. The task is to write a program to find the Nth term in the below series:

1, 8, 54, 384...

Examples:

Input : 3
Output : 54
For N = 3
Nth term = ( 3*3) * 3!
= 54

Input : 2
Output : 8

On observing carefully, the Nth term in the above series can be generalized as:

Nth term = ( N*N ) * ( N! )

Below is the implementation of the above approach:

C++

 // CPP program to find N-th term of the series:// 1, 8, 54, 384...#include using namespace std; // calculate factorial of Nint fact(int N){    int i, product = 1;    for (i = 1; i <= N; i++)        product = product * i;    return product;} // calculate Nth term of seriesint nthTerm(int N){    return (N * N) * fact(N);} // Driver Functionint main(){    int N = 4;     cout << nthTerm(N);     return 0;}

Java

 // Java program to find N-th term of the series:// 1, 8, 54, 384... import java.io.*; // Main class for main methodclass GFG {    public static int fact(int N)    {        int i, product = 1;        // Calculate factorial of N        for (i = 1; i <= N; i++)            product = product * i;        return product;    }    public static int nthTerm(int N)    {        // By using above formula        return (N * N) * fact(N);    }     public static void main(String[] args)    {        int N = 4; // 4th term is 384         System.out.println(nthTerm(N));    }}

Python 3

 # Python 3 program to find# N-th term of the series:# 1, 8, 54, 384... # calculate factorial of Ndef fact(N):         product = 1    for i in range(1, N + 1):        product = product * i    return product # calculate Nth term of seriesdef nthTerm(N):    return (N * N) * fact(N) # Driver Codeif __name__ =="__main__":    N = 4    print(nthTerm(N)) # This code is contributed# by ChitraNayal

C#

 // C# program to find N-th// term of the series:// 1, 8, 54, 384...using System; class GFG{public static int fact(int N){    int i, product = 1;         // Calculate factorial of N    for (i = 1; i <= N; i++)        product = product * i;    return product;} public static int nthTerm(int N){    // By using above formula    return (N * N) * fact(N);} // Driver Codepublic static void Main(String[] args){    int N = 4; // 4th term is 384     Console.WriteLine(nthTerm(N));}} // This code is contributed// by Kirti_Mangal



Javascript


Output:
384

Time Complexity: O(N)

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