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Triangle: T(n,k), k<=n: commutative groupoids with n elements and k idempotents.
3

%I #10 Dec 19 2015 09:50:55

%S 1,0,1,1,2,1,38,57,27,7,13872,18544,9280,2080,192,83360520,104208775,

%T 52110500,13035000,1632750,82355

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

%H <a href="/index/Gre#groupoids">Index entries for sequences related to groupoids</a>

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

%K nonn,tabl,more

%O 0,5

%A _Christian G. Bower_, May 15 1998