Framing this differently, a prime congruent to x mod b is as likely to be followed by a prime congruent to y mod b as a prime congruent to -y mod b is to be fol

Framing this differently, a prime congruent to x mod b is as likely to be followed by a prime congruent to y mod b as a prime congruent to -y mod b is to be followed by one congruent to -x mod b.