A079174 Number of isomorphism classes of non-associative closed binary operations on a set of order n, listed by class size.

0, 2, 3, 1, 12, 71, 3222, 0, 1, 14, 23, 270, 495, 48748, 178932213

Offset

1,2

Comments

A079174(n)+A079175(n)=A079171(n)

Elements per row: 1,2,4,8,16,30,60,96 (A027423, number of positive divisors of n!)

First four rows: 0; 2,3; 1,12,71,3222; 0,1,14,23,270,495,48748,178932213

The sum of each row n is given by A079173(n).

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. A079172, A079173, A079175.

Sequence in context: A276012 A176701 A107415 * A204137 A102583 A030780

Adjacent sequences: A079171 A079172 A079173 * A079175 A079176 A079177

Keyword

nonn,tabf

Author

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

Status

approved