A079187 Number of isomorphism classes of non-anti-commutative closed binary operations (groupoids) on a set of order n.

1, 4, 2334, 147124304, 2216860823492185, 13395780829563177947362200, 48974776899548402559651008669035131863, 151979850442580207421627199010701131897617064179661376, 534046142973031436667769900555231150876473571233474760878454735694121879

Offset: 1

Author

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

Keywords

• nonn

Comments

Each a(n) is equal to the sum of the elements in row n of A079188.

Links

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

Crossrefs

Cf. A079186, A079188, A079190.

Formula

a(n) = A001329(n) - A079190(n), n > 1.

Extensions

Edited, corrected and extended by Christian G. Bower, Dec 12 2003

a(9) from Sean A. Irvine, Aug 03 2025