A079195 Number of non-associative commutative closed binary operations on a set of order n.

0, 0, 2, 666, 1047436, 30517547395, 21936950639192784, 459986536544739894613595, 324518553658426726783148869733112

Offset: 0

Author

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

Keywords

• nonn

Links

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

Crossrefs

Cf. A023813, A023815, A079192, A079196 (isomorphism classes), A079197, A079198.

Formula

A079192(n) + a(n) + A079198(n) + A023815(n) = A002489(n).

a(n) = Sum_{k>=1} A079197(n,k)*A079210(n,k).

a(n) = A023813(n) - A023815(n). - Andrew Howroyd, Jan 26 2022

Extensions

a(0)=0 prepended and a(5)-a(8) added by Andrew Howroyd, Jan 26 2022