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 A090599 #11 Feb 16 2025 08:32:52 %S A090599 1,4,81,16384,48828125,2821109907456,3909821048582988049, %T A090599 154742504910672534362390528,202755595904452569706561330872953769, %U A090599 10000000000000000000000000000000000000000000000 %N A090599 Number of n-element labeled commutative groupoids with an identity. %C A090599 Also labeled commutative groupoids with an absorbant (zero) element. %H A090599 Eric Postpischil <a href="http://groups.google.com/groups?&hl=en&lr=&ie=UTF-8&selm=11802%40shlump.nac.dec.com&rnum=2">Posting to sci.math newsgroup, May 21 1990</a> %H A090599 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Groupoid.html">Groupoid.</a> %H A090599 <a href="/index/Gre#groupoids">Index entries for sequences related to groupoids</a> %F A090599 a(n) = n^(1+binomial(n, 2)) %Y A090599 a(n) = A076113(n)*n. Cf. A038017. %K A090599 nonn %O A090599 1,2 %A A090599 _Christian G. Bower_, Dec 05 2003