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 A175882 #10 Jan 23 2022 18:15:29 %S A175882 1,0,12,19440,4293918720,298022460937500000, %T A175882 10314424627908807366593740800, %U A175882 256923577502496762167593902921782457650400,6277101735385253516143083463326608130132905949327651766272,196627050475552807506414708879663572595247698231546775823411085055396409324160 %N A175882 Number of groupoids of order n with no identity element. %H A175882 Andrew Howroyd, <a href="/A175882/b175882.txt">Table of n, a(n) for n = 0..20</a> %H A175882 ProofWiki, <a href="http://www.proofwiki.org/wiki/Count_of_Binary_Operations_Without_Identity">Count of Binary Operations Without Identity</a> %F A175882 a(n) = n^(n^2) - n^(((n-1)^2)+1) = A002489(n) - A090602(n). %o A175882 (PARI) a(n) = n^(n^2) - n^(((n-1)^2)+1) \\ _Andrew Howroyd_, Jan 23 2022 %Y A175882 Cf. A002489, A090602. %K A175882 nonn %O A175882 0,3 %A A175882 _Matt Westwood_, Dec 05 2010 %E A175882 a(0)=1 prepended and terms a(7) and beyond from _Andrew Howroyd_, Jan 23 2022