[seqfan] Re: A002094 from 1875 needs more terms

Sean A. Irvine sairvin at gmail.com
Sat Mar 17 22:12:51 CET 2018


I get by explicit computation

2, 5, 10, 25, 56, 139, 338, 852, 2145, 5513, 14196, 36962, 96641, 254279,
671640, 1781840

Computed by using nauty to generate trees of maximum degree 4, then either
adding one edge making a multigraph or one edge to make a cycle.  This
matches the more extensive set of terms computed by R. J. Mathar.

Sean.

On 18 March 2018 at 07:20, Neil Sloane <njasloane at gmail.com> wrote:

> Richard, Thanks for figuring out the correct definition!  I have changed
> the definition accordingly.
>
> It would be nice to have more terms, even if they were found by direct
> enumeration using one
> of the methods that Richard suggests - both as a check on Schiff's values,
> and in the hope
> that given enough terms we could guess a generating function.
>
> Best regards
> Neil
>
> Neil J. A. Sloane, President, OEIS Foundation.
> 11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
> Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
>
> On Sat, Mar 17, 2018 at 1:08 PM, Hugo Pfoertner <yae9911 at gmail.com> wrote:
>
> > The German in Schiff's article is difficult to understand, but it is my
> > impression that at the time of writing the meaning of "alcohol radical"
> was
> > different from the modern use, where it means an "-OH" attached to a
> > hydrocarbon.
> > https://www.britannica.com/science/alcohol/Structure-and-
> > classification-of-alcohols
> > So perhaps the name of the sequence should be adapted to modern chemical
> > terminology and "alcohol" be dropped. The title of Richard's
> illustrations
> > might be a candidate for a less misleading sequence title.
> >
> > Schiff 's Hydrocarbons with a Single Ring
> >
> > Hugo Pfoertner
> >
> > On Sat, Mar 17, 2018 at 5:44 PM, Richard J. Mathar <
> mathar at mpia-hd.mpg.de>
> > wrote:
> >
> > > In response to http://list.seqfan.eu/pipermail/seqfan/2018-March/
> > > 018463.html :
> > >
> > > As an appetizer I added illustrations for the first few terms (as far
> as
> > I
> > > understand the compositions) to http://oeis.org/A002094 .
> > >
> > > RJM
> > >
> > > --
> > > Seqfan Mailing list - http://list.seqfan.eu/
> > >
> >
> > --
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> >
>
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