Ruby program to print first n Fibonacci Seqeunce

Question

Newbie here! Trying to implement a program to print the first 20 Fibonacci numbers in Ruby. I've managed to create a program which generates the nth number, but I want to produce all from 0 through to 20.

Is there a simple way to do this or do I need to rewrite the whole program?

CURRENT CODE

def fib(n)
   if n < 1 
     return 0 
       elsif n == 1
     return 1 
    else fib(n-2) + fib(n-1)
  end 
end

puts fib(20)

CURRENT OUTPUT EXAMPLE

6765

DESIRED OUTCOME

0
1
1
2
3
5
8
13
21
34
55
89
144
233
377
610
987
1597
2584
4181
6765

Answer 1

Printing each value is easier with a button-up approach where you start at 0 and 1 and calculate each following value based on its predecessors, e.g.:

i, j = 0, 1

puts i
puts j

21.times do
  k = i + j
  puts k
  i, j = j, k
end

You could turn the above into an Enumerator:

fib = Enumerator.new do |y|
  i, j = 0, 1

  y << i
  y << j

  loop do
    k = i + j
    y << k
    i, j = j, k
  end
end

Which will generate the sequence:

fib.take(21)
#=> [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144,
#    233, 377, 610, 987, 1597, 2584, 4181, 6765]