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A038021 Triangle: T(n,k), k<=n: commutative groupoids with n elements and k idempotents. 3
1, 0, 1, 1, 2, 1, 38, 57, 27, 7, 13872, 18544, 9280, 2080, 192, 83360520, 104208775, 52110500, 13035000, 1632750, 82355 (list; table; graph; refs; listen; history; text; internal format)
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

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Last modified August 10 03:28 EDT 2022. Contains 356029 sequences. (Running on oeis4.)