easter — print the date of Easter in one or more years
easter prints the date(s) of Easter in one or more years.
year can be negative or positive, and is a Proleptic Gregorian year number.
print a Proleptic Gregorian calendar
easter was originally part of Daniel J. Bernstein's libtai toolset in 1999.
Original code and documentation by Daniel J. Bernstein.
Documentation modernizations by Jonathan de Boyne Pollard.