[seqfan] Re: New Printer's Errors from JMF

Eric Angelini Eric.Angelini at kntv.be
Thu Feb 19 13:38:19 CET 2009

Thanks Richard,
I guess JMF is aware of that -- his pgm forbids
things like 2^3^4. The (too short and ambiguous)
definition was provided by me.
I'll try to fix that together with him -- but
the general idea was there, don't you agree? is
there one ambiguous formula in the list he sub-
mitted? Anyway, back to the study...

-----Message d'origine-----
De : seqfan-bounces at list.seqfan.eu
[mailto:seqfan-bounces at list.seqfan.eu] 
De la part de Richard Mathar
Envoyé : jeudi 19 février 2009 13:23
À : seqfan at seqfan.eu
Objet : [seqfan] Re: New Printer's Errors from JMF

ea> From seqfan-bounces at list.seqfan.eu Thu Feb 19 12:34:22 2009
ea> Date: Thu, 19 Feb 2009 12:00:50 +0100
ea> From: "Eric Angelini" <Eric.Angelini at kntv.be>
ea> To: "Sequence Fanatics Discussion list" <seqfan at list.seqfan.eu>
ea> Subject: [seqfan]  New Printer's Errors from JMF
ea> Hello SeqFans,
ea> Jean-Marc Falcoz has computed this list yesterday:
ea> http://odafin.chez.com/decompo.gif
ea> ... for itengers 0 -> 120000
ea> Is this worth the OEIS? (I personally love them!)
ea> The rule says:
ea>     "Insert between each digit of N one of those symbols:
ea>       *
ea>       /
ea>       + 
ea>       -
ea>       ^
ea>      and see if N reproduces itself after computation"

This is ill-defined, because it does not specify the associative rules
(=implicit parentheses). These are part of any higher 
programming language, neither evident nor universal. For this reason
they need to be defined in detail.
Take the example of 2^3^4 (which some people think is well-defined,
though it isn't). See my comment in A145021.

Richard Mathar


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