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