[seqfan] Re: Question regarding A174283

M. F. Hasler oeis at hasler.fr
Mon Oct 12 16:59:06 CEST 2020


On Sun, Oct 11, 2020 at 5:28 PM Rainer Rosenthal <r.rosenthal at web.de> wrote:

> A048211 : The terms of this sequence consider only series and parallel
> combinations; A174283 considers bridge combinations as well. - Jon E.
> Schoenfield, Sep 02 2013
> ~~~~~~~~~~~~
> For bridge combinations there is A174285 = 0, 0, 0, 0, 1, 3, ...
> So I expect A174283 to be the sum, but  A174283 = 1, 2, 4, 9, 23, 57, ...
>

A174285 says "...confined to  5 arms...".
So the additional one, counted in A174283(6), probably has more than 5
arms...

Also, the idea of  A174283 = A048211 + A174285 will go wrong (in the other
sense)
when the two distinct constructions yield common values, viz
# ( A ∪ B ) = # A + # B  −  # ( A ∩ B ).

-Maximilian


More information about the SeqFan mailing list