MATLAB: How to build a new matrix

Question

I have a matrix

a = [4;6;8;2;8;2];

And I want it to be like:

b = [7;8;11;12;15;16;3;4;15;16;3;4];

Matrix b is calculated based on following formula:

7 = 4*2-1
8 = 4*2
11 = 6*2-1
12 = 6*2
15 = 8*2-1
16 = 8*2
3 = 2*2-1
4 = 2*2
15 = 8*2-1
16 = 8*2
3 = 2*2-1
4 = 2*2

Answer 1

Something like

 b = reshape(bsxfun(@minus,2*repmat(a,1,2),[1 0])',1,[])