A079181 Number of isomorphism classes of anti-associative closed binary operations on a set of order n, listed by class size.

1, 0, 2, 0, 0, 2, 0, 8, 0, 0, 2, 0, 29, 0, 383, 17366

Offset: 0

Author

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

Keywords

• nonn
• tabf
• more

Comments

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

Examples

			First rows:
  1;
  0;
  2,0;
  0,2,0,8;
  0,0,2,0,29,0,383,17366;
  ...
		

Links

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

Crossrefs

Cf. A027423 (row lengths), A079176, A079177, A079180 (row sums).

Formula

T(n,k) = A079171(n,k) - A079178(n,k).

A079179(n) = Sum_{k>=1} A079210(n,k) * T(n,k).

Extensions

a(0)=1 prepended and a(1) corrected by Kamil Zabielski, Aug 28 2024