Also you have no idea how compelling I found it as a kid that January and October started the same day of the week, as did February and November, unless it was a Leap Year in which case January started the same day as July and February the same day as August. Once more, in retrospect, I understand why everyone in middle school treated me that way.
Source: The Bill James Baseball Abstract, 1986 Edition.
Based on current projections.
Not valid on the Julian calendar.
Does not account for “Mercedonius”, the occasional 22-day month the Romans would sometime stick in the middle of February because they really did not have a clear handle on how to design a good calendar. I mean, they managed to screw up the rule of “leap year every four years” and it took more than a decade before anyone realized, and that isn’t even my joke.
Not counted: all appearances of King Friday The 13th during the Mister Rogers’ Neighborhood marathon as I could not find when that’s scheduled.