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# Program to print the series 2, 1, 4, 3, 6, 5, …. up to N terms

• Last Updated : 18 Mar, 2021

Given a number N, the task is to print the below pattern upto N terms:

2, 1, 4, 3, 6, 5, …. N terms

Examples:

```Input: N = 4
Output: 2, 1, 4, 3

Explanation:
Nth Term = (N % 2 == 0) ? (N - 1) : (N + 1)
1st term = (1 % 2 == 0) ? (1 - 1) : (1 + 1)
= (1 + 1)
= 2
2nd term = (2 % 2 == 0) ? (2 - 1) : (2 + 1)
= (2 - 1)
= 1
3rd term = (3 % 2 == 0) ? (3 - 1) : (3 + 1)
= (3 + 1)
= 4
4th term = (4 % 2 == 0) ? (4 - 1) : (4 + 1)
= (4 - 1)
= 3
Therefore, Series = 2, 1, 4, 3

Input: N = 7
Output: 2, 1, 4, 3, 6, 5, 8```

Formula:

`Nth Term = (N % 2 == 0) ? (N - 1) : (N + 1)`

Below is the solution to above problem:

## C++

 `// C++ program to print the series``// 2, 1, 4, 3, 6, 5, …. up to N terms``#include ``using` `namespace` `std;` `// Function to print the series``void` `printPattern(``int` `N)``{` `    ``for` `(``int` `i = 1; i <= N; i++) {` `        ``// Find and print the ith term``        ``cout <<``" "``<<((i % 2 == 0) ? (i - 1) : (i + 1));``    ``}``}` `// Driver code``int` `main()``{` `    ``// Get the value of N``    ``int` `N = 10;` `    ``// Print the Series``    ``printPattern(N);` `    ``return` `0;``}`

## Java

 `// Java Program to print the series``// 2, 1, 4, 3, 6, 5, …. up to N terms` `import` `java.util.*;``import` `java.lang.*;``import` `java.io.*;` `class` `GFG``{``// Function to print the series``static` `void` `printPattern(``int` `N)``{``  ` `    ``for` `(``int` `i = ``1``; i <= N; i++) {``  ` `        ``// Find and print the ith term``        ``System.out.print(``" "``+((i % ``2` `== ``0``) ? (i - ``1``) : (i + ``1``)));``    ``}``}``  ` `// Driver code``public` `static` `void` `main(String args[])``{``  ` `    ``// Get the value of N``    ``int` `N = ``10``;``  ` `    ``// Print the Series``    ``printPattern(N);``  ` `}``}`

## Python3

 `# Python program to print the series``# 2, 1, 4, 3, 6, 5, …. up to N terms` `# Function to print the series``def` `printPattern(N):``    ``for` `i ``in` `range``(``1``, N ``+` `1``):``        ` `        ``# Find and print the ith term``        ``print``(i ``-` `1` `if` `i ``%` `2` `=``=` `0``                    ``else` `i ``+` `1``, end ``=` `" "``)` `# Driver code``N ``=` `10``printPattern(N)` `# This code is contributed by Shrikant13`

## C#

 `// C# program to print the series``// 2, 1, 4, 3, 6, 5, …. up to N terms``using` `System;` `class` `GFG``{``// Function to print the series``public` `void` `printPattern(``int` `N)``{` `    ``for` `(``int` `i = 1; i <= N; i++)``    ``{` `        ``// Find and print the ith term``        ``int` `a = ((i % 2 == 0) ?``                      ``(i - 1) : (i + 1));``        ``Console.Write(``" {0}"``, a);``    ``}``}` `// Driver code``public` `static` `void` `Main()``{``    ``GFG g = ``new` `GFG();``    ` `    ``// Get the value of N``    ``int` `N = 10;` `    ``// Print the Series``    ``g.printPattern(N);``}``}` `// This code is contributed``// by Soumik`

## PHP

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## Javascript

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Output:
`2 1 4 3 6 5 8 7 10 9`

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