A079185 Number of isomorphism classes of commutative closed binary operations (groupoids) on a set of order n, listed by class size.

1, 0, 4, 1, 4, 8, 116, 0, 0, 0, 8, 0, 28, 504, 43428

Offset: 1

Author

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

Keywords

• nonn
• tabf

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: 1; 0,4; 1,4,8,116; 0,0,0,8,0,28,504,43428

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

• C. van den Bosch, Closed binary operations on small sets
• Index entries for sequences related to groupoids

Crossrefs

Cf. A001425, A023183, A079184. a(n, A027423(n)) = A030255(n).