Let's see. We already have lots of fibonacci generator threads, like (OT) Fibonacci numbers in Ruby - final shot - 24 chars, Golfing a fibonacci number generator, Fibonacci Numbers, Fibonacci numbers (again)1 Fibonacci golf with one state variable1. We can use some ideas from those threads.

Firstly, modifying my dc solution, we get 

dc -e1dp[pdsd+ldrlxx]dsxx|head -20

[download]

Then there's the ruby one you can adapt 

ruby '-wex=i=1;20.times{p x;x+=i=x-i}'

[download]

I'll try to improve these and update this node later if I can.

Update: longer variants of the ruby line are: 

ruby '-wep 1,x=1;18.times{p x=(x/0.618).round}'

[download]
or 
ruby '-we20.times{|x|p((1.61803**x/1.382).round)}'

[download]

Update: I forgot to tell, but for just the first twenty numbers, the shorter dc one should work fine as well: 

dc -e1pd[pdk+Krlxx]dsxx|head -20

[download]
Update: The following which doesn't use head is even shorter 
dc -e1pd[rpdk+Kd6666\>x]dsxx

[download]
The following is yet one character shorter, but it takes some seconds to compute because it computes square roots to thousands of decimal places. 
dc -e1pd[rpdk+Kdv66\>x]dsxx

[download]
Update: Even shorter and does not have the speed penalty is this: 
dc -e1pd[pdk+KrdZ5\>x]dsxx

[download]

Update: And you can cut one more character: 

dc -e1d[prdk+KdZ5\>x]dsxx

[download]

Update 2008 oct 5: added two links marked by 1.

In reply to Re: Fibo Golf challenge on 3 monkeys by ambrus
in thread Fibo Golf challenge on 3 monkeys by RMGir

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