A barcode is made of white and black lines. A barcode always begins and ends width a black line. Each line has is of thickness 1 or 2, and the whole barcode is of thickness 12.
How many different barcodes are there (we read a barcode from left to right).
I know that I'm required to show some effort, yet I really don't have a clue about this problem. Can you give me any hints?