Not sure about OP's equations. He has done well in presenting his findings. It would be interesting to hear more of his rationale, too.

It did get me to pondering the Western thought of 13 being unlucky. What if this was introduced during the Middle Ages (and earlier) to lead the average man away from the truth...in the heavens.

Something Wonder Full is happening! Whether we approach it feeling trepidation or joy is a matter of personal experience.