Search the game tree of a repeat-a-number game; see https://math.stackexchange.com/questions/4605602

Question4605602.java

import java.util.BitSet;

public class Question4605602 {
    static BitSet used = new BitSet();

    public static void main(String [] args) {
        System.out.println(value(1));
    }
    
    static boolean value(int move) {
        if (used.get(move))
            return true;
        used.set(move);
        boolean losing = value ((int) Math.floor(move / 3)) || value (2 * move + 1) || value (2 * move + 5);
        used.clear(move);
        return !losing;
    }
}