This is usually used to make it unambiguous that you're talking about
bit flags. 1, 2, and 4 will make most programmers realize that we're
talking about a sequence of powers of 2; not everyone will instantly know
that 1<<14 is 16384. The compiler will do these computations for
you, so it will not slow the program down. It's all about clarity.
You'll sometimes also see these things written in hexadecimal, because
that maps more closely to the underlying binary representation than decimal
constants and can be more compact.