How do I generate the first n prime numbers?

Question

I am learning Ruby and doing some math stuff. One of the things I want to do is generate prime numbers.

I want to generate the first ten prime numbers and the first ten

Answer 1

Implemented the Sieve of Eratosthene (more or less)

def primes(size)
    arr=(0..size).to_a
    arr[0]=nil
    arr[1]=nil
    max=size
    (size/2+1).times do |n|
        if(arr[n]!=nil) then
            cnt=2*n
            while cnt <= max do
                arr[cnt]=nil
                cnt+=n
            end
        end
    end
    arr.compact!
end

Moreover here is a one-liner I like a lot

def primes_c a
    p=[];(2..a).each{|n| p.any?{|l|n%l==0}?nil:p.push(n)};p
end

Of course those will find the primes in the first n numbers, not the first n primes, but I think an adaptation won't require much effort.