is.prime<-function(n)
{
if(n==2) return(1);
if(n==1 || n%%2==0) return(0);
m<-floor(sqrt(n))+1;
for(i in 2:m) { if(n %% i ==0) return(0); }
return(1);
}
print.primes<-function(n, h)
{
z<-tapply(1:n,as.factor(1:n),is.prime);
primes<-(1:n)[z==1];
plot(primes, col="blue", type="b", pch=5,
xlab="Index",ylab="");
text(1:length(primes),primes+h,labels=primes);
return(length(primes));
}
print.primes(100,2);