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A079195
Number of non-associative commutative closed binary operations on a set of order n.
13
0, 0, 2, 666, 1047436, 30517547395, 21936950639192784, 459986536544739894613595, 324518553658426726783148869733112
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OFFSET
0,3
LINKS
Table of n, a(n) for n=0..8.
C. van den Bosch,
Closed binary operations on small sets
Index entries for sequences related to groupoids
FORMULA
A079192
(n) + a(n) +
A079198
(n) +
A023815
(n) =
A002489
(n).
a(n) = Sum_{k>=1}
A079197
(n,k)*
A079210
(n,k).
a(n) =
A023813
(n) -
A023815
(n). -
Andrew Howroyd
, Jan 26 2022
CROSSREFS
Cf.
A023813
,
A023815
,
A079192
,
A079196
(isomorphism classes),
A079197
,
A079198
.
Sequence in context:
A046856
A156938
A285221
*
A120123
A140014
A188698
Adjacent sequences:
A079192
A079193
A079194
*
A079196
A079197
A079198
KEYWORD
nonn
AUTHOR
Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003
EXTENSIONS
a(0)=0 prepended and a(5)-a(8) added by
Andrew Howroyd
, Jan 26 2022
STATUS
approved
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Last modified August 29 15:03 EDT 2024. Contains 375517 sequences. (Running on oeis4.)