User blog comment:Pellucidar12/Idea for a function (Hyperprime counting functions)/@comment-5029411-20170723214637/@comment-2607:FB90:985C:F190:C5CA:39B5:4656:6024-20170724201012

Actually it does. 2 is an even integer but 2 is also the first positive even integer and thus has no preceding basic even factor(2 is the factor that makes it impossible for any numbers other than itself to be prime). So it still does work for 2