A038021 Triangle: T(n,k), k<=n: commutative groupoids with n elements and k idempotents.

1, 0, 1, 1, 2, 1, 38, 57, 27, 7, 13872, 18544, 9280, 2080, 192, 83360520, 104208775, 52110500, 13035000, 1632750, 82355

Offset

0,5

Links

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

Index entries for sequences related to groupoids

Crossrefs

Cf. A001329, A001425, A030257, A030260, A030263.

Sequence in context: A127608 A038022 A173838 * A127609 A228860 A271204

Adjacent sequences: A038018 A038019 A038020 * A038022 A038023 A038024

Keyword

nonn,tabl,more

Author

Christian G. Bower, May 15 1998

Status

approved