All entries of array except certain indices in octave/matlab

In Octave or Matlab, some times one needs to eliminate certain elements in an array.

For example, if

a = [10,20,30,40,50,60];

and suppose I want to create a matrix "b" such that it has all the elements of "a" except 20 and 40. This can be achieved by:

b = a(1:end~=2&1:end~=4);

The result is:

b = 10 30 50 60