This is even shorter, but it prints newlines, not spaces. It's better than the perl one because it calculates all digits. 

dc -e1d[pdsd+ldrlxx]dsxx

[download]
If it's enough to have the first say 40 elements of the sequence (depending on an internal limitation of dc) then this is 2 chars shorter: 
dc -e1d[pdk+Krlxx]dsxx

[download]

If you insist on spaces, here's a version: 

dc -e1d[ddn32Psd+ldrlxx]dsxx

[download]

These depend on the dc extension command r (and the last one on n and P too), but these are present in both GNU dc and FreeBSD dc, so it might be portable now.

Update 2006 nov 15:

This is slightly longer than the above but is still interesting: 

dc -e'1[pdd5**v1++2/lxx]dsxx'

[download]

Update 2007 jul 17: some explanation in Re^3: Fibo Golf challenge on 3 monkeys.

In reply to Re: Fibonacci numbers (again) by ambrus
in thread Fibonacci numbers (again) by sh1tn

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.