A slightly different approach:

import java.util.Scanner;
class Solution
{
        public static void main(String args[])
        {
                Scanner scnr = new Scanner(System.in);
                int day = scnr.nextInt();
                int liked = 5/2, cumulative = 2;

                for(int i=1; i<day; i++)
                {
                        liked = (liked * 3)/2;
                        cumulative += liked;
                }

                System.out.print(cumulative);
        }
}