hi, JLatham !

I got curious about all of this and did a lot of research and testing.
The results of the tests indicate that the formula just provided is valid for all years from 1900 through 2033
with the exception that it gives a wrong answer in 2079. Years after 2033 generate irregular errors.
The following change to that formula will provide uninterrupted correct results from 1900 through 2033:
=IF(A3<2079,FLOOR(DATE(A3,5,DAY(MINUTE(A3/38)/2+56)),7)-34,FLOOR(DATE(A3,5,DAY(MINUTE(A3/38)/2+57)),7)-34)

it's a great development, thanks for sharing it :D

also, it is possible a little streamlining to the formula and avoid the 'conditional' IF function [same results]...
=floor(date(a3,5,day(minute(a3/38)/2+56+(a3=2079))),7)-34

my US $0.02
regards,
hector.

Essentially, in 2079 we have to add 1 week into the formula. References are
http://aa.usno.navy.mil/faq/docs/easter.html
and the table at
http://www.smart.net/~mmontes/freq3.html

The results of my research can be seen in this workbook at my site:
http://www.jlathamsite.com/uploads/E...omparisons.xls

Enjoy!