https://en.wikipedia.org/wiki/Doomsday_rule https://en.wikipedia.org/wiki/Doomsday_rule Basically the following days have the same day of the week: Jan 3 or 4

https://en.wikipedia.org/wiki/Doomsday_rule https://en.wikipedia.org/wiki/Doomsday_rule Basically the following days have the same day of the week: Jan 3 or 4 on a leap year, last day of February, all the even pairs day / month days after that (4/4, 6/6, 8/8, 10/10, 12/12), 7/11 and 11/7, 9/5 and 5/9.