[seqfan] Re: Gen. Functs. A039219

Hagen von Eitzen hagen at von-eitzen.de
Wed Sep 16 08:36:41 CEST 2009


franktaw at netscape.net schrieb:
> And, unfortunately, there are quite a few g.f.s in the OEIS that are 
> off by a factor of x or x^2 or so.  I fix these when I see them, but a 
> review of all the g.f.s in the database is not a realistic possibility.
>
>   
I remember from sequences esp. those that are rather lists than 
functions N -> N
then when I was able to add a g.f. the formula often looks more natural 
without the
extra factor x (i.e. if the list were given as a(0), a(1), ... instead), 
hence I can
understand how it may happen that one forgets these offset factors.
In a perfect world, such offset problems should be detectable mostly 
automatically,
provided the g.f.s. can be reliably extracted syntactically and 
translated to a syntax
feedable to, say, pari and then compare GF+O(x^10) with the first members
of the sequence ...
However, I'm afraid reliable extraction and unified syntax are somewhat 
problematic.

Hagen




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