A038023 Triangle: T(n,k), k<=n: commutative groupoids with a nontrivial symmetry with n elements and k idempotents.

0, 0, 0, 0, 0, 0, 3, 6, 0, 4, 96, 214, 128, 64, 38, 54248, 83925, 54223, 28254, 10223, 1894

Offset

0,7

Links

Table of n, a(n) for n=0..20.

Index entries for sequences related to groupoids

Formula

Difference of A038021 and A038022.

Crossrefs

Cf. A001329, A001425, A030259, A030262, A030265.

Sequence in context: A334477 A278488 A367325 * A008954 A169890 A181907

Adjacent sequences: A038020 A038021 A038022 * A038024 A038025 A038026

Keyword

nonn,tabl,more

Author

Christian G. Bower, May 15 1998

Status

approved