This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A079188 #9 Aug 03 2025 23:40:42 %S A079188 0,0,4,1,4,44,2285,0,0,0,24,64,212,35240,147088764 %N A079188 Number of isomorphism classes of non-anti-commutative closed binary operations on a set of order n, listed by class size. %C A079188 Elements per row: 1,2,4,8,16,30,... (given by A027423, number of positive divisors of n!) %C A079188 A079176(n) is equal to the sum of the products of each element in row n of this sequence and the corresponding element of A079210. %C A079188 The sum of each row n of this sequence is given by A079177(n). %H A079188 C. van den Bosch, <a href="http://cosmos.ucc.ie/~cjvdb1/html/binops.shtml">Closed binary operations on small sets</a> %H A079188 <a href="/index/Gre#groupoids">Index entries for sequences related to groupoids</a> %F A079188 a(n) = A079171(n) - A079191(n). %e A079188 First four rows: %e A079188 0; %e A079188 0, 4; %e A079188 1, 4, 44, 2285; %e A079188 0, 0, 0, 24, 64, 212, 35240, 147088764. %Y A079188 Cf. A027423, A079171, A079186, A079187, A079191. %K A079188 nonn,tabf %O A079188 1,3 %A A079188 Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003