A079197 Number of isomorphism classes of non-associative commutative closed binary operations on a set of order n, listed by class size.

0, 0, 1, 1, 4, 5, 107, 0, 0, 0, 5, 0, 28, 488, 43389

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: A005512 A331584 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