years <- 2008:2121
xmas <- as.POSIXlt(paste0(years, '/12/25'))
years[xmas$wday==0]



xmas=seq(as.Date("2008/12/25"), as.Date("2121/12/25"), by="year")
as.numeric(format(xmas[weekdays(xmas)== 'Sunday'], "%Y"))


with(list(years=2008:2121), years[weekdays(ISOdate(years, 12, 25)) == "Sunday"])


subset(data.frame(years=2008:2121), weekdays(ISOdate(years, 12, 25)) == "Sunday")$years



Sys.setlocale(cat="LC_ALL", "en")


Sys.setlocale("LC_ALL", "English")