Number prime numbers requested, starting at 2.
Maximum is 1e8 or 100,000,000.
Value
A vector of length n containing prime numbers, in order,
starting at 2. Note that 1 is prime, but is never included here. I.e.,
primes(1) equals c(2).
Details
This routine is brute-force and works well for the low primes, i.e.,
for n less than a couple hundred thousand. It is not particularly
efficient for large n. For example, primes(2000) on a
Windows laptop takes approximately 4 seconds,
while primes(5000) takes approximately 30 seconds.
# NOT RUN {primes(4) # c(2,3,5,7) # Prime pairs in the first 100p <- primes(100)
p.diff <- diff(p)
cbind(p[-length(p)][p.diff==2], p[-1][p.diff==2])
# }