查找系列 1、3、12、60、360 的第 N 项的程序...

给定一个数字 N。任务是编写一个程序来找到以下系列中的第 N 项：

1, 3, 12, 60, 360…

例子：

Input: 2
Output: 3

Input: 4
Output: 60

方法：思路是先求数（N+1）的阶乘，即（N+1）！
现在，上述系列中的第 N 项将是：

N-th term = (N+1)!/2

下面是上述方法的实现：

C++

// CPP program to find N-th term of the series:
// 1, 3, 12, 60, 360…
 
#include 
using namespace std;
 
// Function to find factorial of N
int factorial(int N)
{
    int fact = 1;
 
    for (int i = 1; i <= N; i++)
        fact = fact * i;
 
    // return factorial of N+1
    return fact;
}
 
// calculate Nth term of series
int nthTerm(int N)
{
    return (factorial(N + 1) / 2);
}
 
// Driver Function
int main()
{
 
    // Taking n as 6
    int N = 6;
 
    // Printing the nth term
    cout << nthTerm(N);
 
    return 0;
}

Java

// Java program to find N-th
// term of the series:
// 1, 3, 12, 60, 360
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
class GFG {
 
    // Function to find factorial of N
    static int factorial(int N)
    {
        int fact = 1;
 
        for (int i = 1; i <= N; i++)
            fact = fact * i;
 
        // return factorial of N
        return fact;
    }
 
    // calculate Nth term of series
    static int nthTerm(int N)
    {
        return (factorial(N + 1) / 2);
    }
 
    // Driver Code
    public static void main(String args[])
    {
 
        // Taking  n as 6
        int N = 6;
 
        // Printing the nth term
        System.out.println(nthTerm(N));
    }
}

Python3

# Python 3 program to find
# N-th term of the series:
# 1, 3, 12, 60, 360…
 
# Function for finding
# factorial of N
def factorial(N) :
    fact = 1
    for i in range(1, N + 1) :
        fact = fact * i
 
    # return factorial of N
    return fact
 
# Function for calculating
# Nth term of series
def nthTerm(N) :
 
    # return nth term
    return (factorial(N + 1) // 2)
 
# Driver code
if __name__ == "__main__" :
     
    N = 6
 
    # Function Calling
    print(nthTerm(N))

C#

// C# program to find N-th
// term of the series:
// 1, 3, 12, 60, 360
using System;
 
class GFG
{
     
// Function to find factorial of N
static int factorial(int N)
{
    int fact = 1;
 
    for (int i = 1; i <= N; i++)
        fact = fact * i;
 
    // return factorial of N
    return fact;
}
 
// calculate Nth term of series
static int nthTerm(int N)
{
    return (factorial(N + 1) / 2);
}
 
// Driver Code
static void Main()
{
    int N = 6 ;
     
    // Printing the nth term
    Console.WriteLine(nthTerm(N));
}
}
 
// This code is contributed
// by ANKITRAI1

PHP

Javascript

输出：