bday=function(n){
  bday<-1; nm1<-n-1
  for(j in 1:nm1){bday=bday*((365-j)/365)}
  bday<-1-bday
  return(bday)
  }
bday(10)

# Change values of n
for(i in 10:25){a[i]<-bday(i)}
cbind(10:25,a[10:25])