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%I #19 Feb 02 2023 15:26:12
%S 0,0,0,2,0,2,9,54,0,30,15376,12664,14304,4096,3187
%N Triangle: T(n,k), k<=n: groupoids with a nontrivial symmetry with n elements and k idempotents.
%H <a href="/index/Gre#groupoids">Index entries for sequences related to groupoids</a>
%F Difference of A038018 and A038019.
%e Triangle begins:
%e 0;
%e 0, 0;
%e 2, 0, 2;
%e 9, 54, 0, 30;
%e 15376, 12664, 14304, 4096, 3187;
%e ...
%Y Row sums are A030246.
%Y Main diagonal is A030249.
%Y Columns k=0..1 are A030252, A030254.
%Y Cf. A001329, A030248, A030251, A030271.
%K nonn,tabl,more
%O 0,4
%A _Christian G. Bower_, May 15 1998
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