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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; 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

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 A041409

Adjacent sequences:  A079194 A079195 A079196 * A079198 A079199 A079200

KEYWORD

nonn,tabf

AUTHOR

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

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Last modified February 17 17:51 EST 2012. Contains 206061 sequences.