C :

#include<stdio.h>

void main(){
	int i,n;
	scanf("%d",&n);
	
	for(i=1;i<=n;i++){
		if(3*i-2<=n){
			printf("%d\n",3*i-2);
		}
	}
}

C++ :

#include<iostream>
using namespace std;

int main() {
	int i,n;
	cin>>n;
	for(i = 1;i <= n;i = i + 3){
		cout<<i<<endl;
	}
}

Java :

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		for(int i=1;i<=n;i=i+3){
		System.out.println(i);	
		}
	}

}

Python :

n = int(input())
print(1)
a = 1
for i in range(1, n + 1):
    if i - a == 3:
        print(i)
        a += 3