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A079197 Number of isomorphism classes of non-associative commutative closed binary operations on a set of order n, listed by class size. 13
0, 0, 1, 1, 4, 5, 107, 0, 0, 0, 5, 0, 28, 488, 43389 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

A079194(n)+A079197(n)+A079200(n)+A079201(n)=A079171(n).

Elements per row: 1,2,4,8,16,30,... (given by A027423, number of positive divisors of n!)

First four rows: 0; 0,1; 1,4,5,107; 0,0,0,5,0,28,488,43389

A079195(x) is equal to the sum of the products of each element in row x of this sequence and the corresponding element of A079210.

The sum of each row x of this sequence is given by A079196(x).

LINKS

Table of n, a(n) for n=1..15.

C. van den Bosch, Closed binary operations on small sets

Index entries for sequences related to groupoids

CROSSREFS

Cf. A079194, A079198, A079199, A079200, A079201.

Sequence in context: A041173 A005512 A052320 * A113942 A073129 A270551

Adjacent sequences:  A079194 A079195 A079196 * A079198 A079199 A079200

KEYWORD

nonn,tabf

AUTHOR

Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003

STATUS

approved

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Last modified May 24 20:53 EDT 2019. Contains 323534 sequences. (Running on oeis4.)