Page "Church–Turing thesis" Paragraph 58

: From this list we extract an increasing sublist: put m < sub > 0 </ sub >= n < sub > 0 </ sub >, after finitely many steps we find an n < sub > k </ sub > such that n < sub > k </ sub > > m < sub > 0 </ sub >, put m < sub > 1 </ sub >= n < sub > k </ sub >.

We repeat this procedure to find m < sub > 2 </ sub > > m < sub > 1 </ sub >, etc.

this yields an effective listing of the subset B =