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 A079173 #14 Jul 19 2025 10:11:58 %S A079173 0,5,3306,178981764,2483527537092910,14325590003318891522247046, %T A079173 50976900301814584087291487087212542367, %U A079173 155682086691137947272042502251643461917498831796991599,541851439802559836957713164869818405872834954135521300809796661279574643 %N A079173 Number of isomorphism classes of non-associative closed binary operations on a set of order n. %C A079173 Each a(n) is equal to the sum of the elements in row n of A079174. %H A079173 Christian van den Bosch, <a href="https://web.archive.org/web/20071014230143/http://cosmos.ucc.ie/~cjvdb1/html/binops.shtml">Closed binary operations on small sets</a>. [Wayback Machine link] %H A079173 <a href="/index/Gre#groupoids">Index entries for sequences related to groupoids</a>. %F A079173 a(n) = A001329(n) - A027851(n). %Y A079173 Cf. A001329, A027851, A079172, A079174. %K A079173 nonn %O A079173 1,2 %A A079173 Christian van den Bosch (cjb(AT)cjb.ie), Jan 03 2003 %E A079173 More terms from _Christian G. Bower_, Nov 26 2003 %E A079173 a(8)-a(9) added using the data at A001329 and A027851 by _Amiram Eldar_, Jul 19 2025