A079184 Number of isomorphism classes of non-commutative closed binary operations on a set of order n, listed by class size.

0, 4, 2, 2, 8, 70, 3121, 2, 1, 14, 22, 275, 467, 48306, 178888897

Offset

1,2

Comments

A079184(n)+A079185(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; 4,2; 2,8,70,3121; 2,1,14,22,275,467,48306,178888897

A079176(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 n is given by A079177(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. A079182, A079183, A079185.

Sequence in context: A153810 A098134 A079191 * A095800 A055630 A182700

Adjacent sequences: A079181 A079182 A079183 * A079185 A079186 A079187

Keyword

nonn,tabf

Author

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

Status

approved