[seqfan] intersection patterns of n sets
Joerg Arndt
arndt at jjj.de
Sat Dec 20 10:49:08 CET 2014
Removing all "geometric" restrictions from
https://oeis.org/A250001
and changing "circles" to "sets" we get a
comment that could possibly put into some(*)
sequence:
"a(n+1) is the number of intersection patterns
of n (unlabeled) sets of unlabeled elements."
Now which one would be (*)?
Spoiler below.
SPOILER:
Comment goes on:
"Take n nodes for the sets and put an edge between to
sets whenever they have a nonempty intersection;
take one extra node and put an edge to a set whenever
it has an element that is unique to it."
Yes, sequence (*) is
https://oeis.org/A000088
Is this a comment worthy of being put into A000088 ?
If so, should a similar comment appear in
https://oeis.org/A001349
?
Best regards, jj
More information about the SeqFan
mailing list