cp's OEIS Frontend

A058157 Triangle read by rows: T(n,k) is the number of labeled monoids of order n with k idempotents.

%I A058157 #15 Feb 17 2022 14:19:33
%S A058157 1,2,2,3,18,12,16,180,288,140,30,2640,6540,8380,3020,480,119610,
%T A058157 238200,421020,372360,100362,840,25196052,13786290,26803000,36174600,
%U A058157 22822674,4768624,22080,48687313640,2254725312,2358499080,3849768160,3859581096,1826525120,305498328
%N A058157 Triangle read by rows: T(n,k) is the number of labeled monoids of order n with k idempotents.
%H A058157 <a href="/index/Mo#monoids">Index entries for sequences related to monoids</a>
%F A058157 T(n,k) = A058158(n,k)*n.
%e A058157 Triangle begins:
%e A058157    1;
%e A058157    2,    2;
%e A058157    3,   18,   12;
%e A058157   16,  180,  288,  140;
%e A058157   30, 2640, 6540, 8380, 3020;
%e A058157   ...
%Y A058157 Row sums give A058153.
%Y A058157 Column 1: A034383.
%Y A058157 Main diagonal is A351731.
%Y A058157 Cf. A058137 (isomorphism classes), A058158, A058159 (commutative), A058166.
%K A058157 nonn,tabl
%O A058157 1,2
%A A058157 _Christian G. Bower_, Nov 14 2000
%E A058157 a(30)-a(36) from _Andrew Howroyd_, Feb 15 2022