cp's OEIS Frontend

A058116 Triangle read by rows: T(n,k) is the number of isomorphism classes of commutative semigroups of order n with k idempotents.

%I A058116 #13 Jan 27 2022 18:18:43
%S A058116 1,2,1,5,5,2,16,23,14,5,62,106,93,49,15,342,544,582,422,200,53,3435,
%T A058116 3380,3773,3360,2178,943,222,97061,30788,27222,26625,21283,12676,5072,
%U A058116 1078
%N A058116 Triangle read by rows: T(n,k) is the number of isomorphism classes of commutative semigroups of order n with k idempotents.
%H A058116 <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a>
%e A058116 Triangle begins:
%e A058116    1;
%e A058116    2,   1;
%e A058116    5,   5,  2;
%e A058116   16,  23, 14,  5;
%e A058116   62, 106, 93, 49, 15;
%e A058116   ...
%Y A058116 Row sums give A001426.
%Y A058116 Main diagonal is A006966(n+1).
%Y A058116 Column 1 is A058117.
%Y A058116 The labeled version is A058167.
%Y A058116 Cf. A058108, A058142.
%K A058116 nonn,tabl,hard,more
%O A058116 1,2
%A A058116 _Christian G. Bower_, Nov 09 2000
%E A058116 a(29)-a(36) from _Andrew Howroyd_, Jan 27 2022