The following works to calculated the date for Easter any given year.
I don't understand why it works ...
=FLOOR.XCL("5/"&DAY(MINUTE(YEAR("1/1/2017")/38)/2+56)&"/"&YEAR("1/1/2017"),7)-34
I'm a novice - in the above, "1/1/2017" is used to provide a year. That could be done a number of ways,
and is not the same way I have the formula stored in a Libreoffice Calc spreadsheet.