My question is the following:

Construct the following sets:

W={n element Z | 1 <= n <= 1 000 000}

X = {n^2 + n | 1 <= n <= 1 000 000, n element Z}

Z = {n | n+1 is prime, 1 <= n <= 1 000 000}

What I'm not confident on is representing the set n from 1 to 1000000 in both Re and Im. This how I went about W:

W = Table[ Complex[n, (0 + j)*(-1)^(i)], {n, 1, 10}, {i, 1, 2}, {j, 0, 1}]

The set I get has all the correct elements, that is n +/-i, and all the n's also, but I want them as one big set, not as subsets. How can I get this? Is there an easier way.

If I'm able to get W, I'm pretty sure I can nail X. Z I already have.

Thanks, Matt