[seqfan] Re: Question regarding some sequences

Sean A. Irvine sairvin at gmail.com
Mon Dec 26 19:57:18 CET 2016


I have a copy of the reference, but no way to scan.

The definition of A036672 is the counting series for the stereo-isomers of
all acyclic hydrocarbons. n is almost certainly the number of carbon atoms.
The acyclic part should be added to the title. And A0036673 is the same
thing, but with triple bonds excluded.  The reference gives a complicated
looking three-variable generating function and cycle-index over A4 which
can produce both these sequences.  There are dependencies on earlier
generating functions as well (i.e. probably not a five minute job to extend
these sequences via that formula or even to type the formula in). These
sequences might be simple sums of some of the other counting series already
present in the OEIS since the reference (as Neil mentions) contains a large
number of sequences many of which are for counting various forms of
alkanes, alkenes, etc.

I will look into this further, but might be a few days.


On 26 December 2016 at 16:25, Natan Consigli <origami.experience at gmail.com>
wrote:

> Dear Seqfans,
>
> I've come across A036672, A014236, I'm having a hard time
> understanding which molecules are counted. Can someone explain me what
> those sequences are exactly?
>
> I think I could better understand it if someone could show me which
> ones are counted in the case of 4 carbon atoms.
>
> thanks in advance,
>
> Natan Consigli
>
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> Seqfan Mailing list - http://list.seqfan.eu/
>


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