How can I integrate select parts of a vector, with a constant step size?

If I have a vector, say, v = [1:1:20], and I want the first term of the cumtrapz(v) to work on [v(1) v(11)], the second term to work on [v(2) v(12)], third on [v(3) v(13)],... e.t.c. For this example, the cumtrapz result would have a maximum of 10 terms.

How can I go about this, please?