[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
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