# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a038021 Showing 1-1 of 1 %I A038021 #10 Dec 19 2015 09:50:55 %S A038021 1,0,1,1,2,1,38,57,27,7,13872,18544,9280,2080,192,83360520,104208775, %T A038021 52110500,13035000,1632750,82355 %N A038021 Triangle: T(n,k), k<=n: commutative groupoids with n elements and k idempotents. %H A038021 Index entries for sequences related to groupoids %Y A038021 Cf. A001329, A001425, A030257, A030260, A030263. %K A038021 nonn,tabl,more %O A038021 0,5 %A A038021 _Christian G. Bower_, May 15 1998 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE