Adding 2 values of old vector into new vector of half size

Suppose you have a vector a = [0; 1; 3; 2; 2; 0; 1; 2]

I am looking for a new vector b, which has half the size of a and stores the sum of two values. Therefore, b will be a summarized version of a, where each value of a is only used once. b should look like this:

b = [1; 5; 2; 3]

Eventually, I would like this to keep going and give me a vector c which does the same with b:

c = [6; 5]

Would this also work with uneven amount of inputs?

Answer 1

[Marcel Kreuzberg]

b = a(1:2:end) + a(2:2:end) (this is not working for uneven amount of inputs)

[Raphael Willi]

thank you anyways