Use 1 instead of 2, makes the bitshift easier.

src/DoublesGame.java

@@ -36,7 +36,7 @@ public class DoublesGame {
 			if(a == 0) {
 				System.out.println("Goodbye!");
 				break;
-			} else if(a != 2 << (n - 1)) {
+			} else if(a != 1 << n) {
 				System.out.println("Wrong answer, try again.");
 			} else {
 				System.out.println("Correct!");

src/Main.cpp

@@ -34,7 +34,7 @@ int main(void) {
 		if(a == 0) {
 			std::cout << "Goodbye!\n";
 			return 0;
-		} else if(a not_eq 2 << (n - 1)) {
+		} else if(a not_eq 1 << n) {
 			std::cout << "Wrong answer, try again.\n";
 		} else {
 			std::cout << "Correct!\n";

src/doublesgame.py

@@ -31,7 +31,7 @@ while True:
     if a is 0:
         print("Goodbye!")
         break
-    elif a is not 2 << (n - 1):
+    elif a is not 1 << n:
         print("Wrong answer, try again.")
     else:
         print("Correct!")

src/doublesgame.sh

@@ -32,7 +32,7 @@ do
 	then
 		echo "Goodbye!"
 		break
-	elif [ $a -ne $((2 << ($n - 1))) ]
+	elif [ $a -ne $((1 << $n)) ]
 	then
 		echo "Wrong answer, try again."
 	else

src/main.c

@@ -33,7 +33,7 @@ int main(void) {
 		if(a == 0) {
 			printf("Goodbye!\n");
 			return 0;
-		} else if(a != 2 << (n - 1)) {
+		} else if(a != 1 << n) {
 			printf("Wrong answer, try again.\n");
 		} else {
 			printf("Correct!\n");