%I A057997
%S A057997 1,2,3,16,280,56448,118594560,4282251214848,3398378138678329344,
%T A057997 75807214831601328114892800
%N A057997 Number of labeled loops (quasigroups with an identity element).
%H A057997 <a href="Sindx_Qua.html#quasigroups">Index entries for sequences related 
               to quasigroups</a>
%Y A057997 a(n)=A000315(n)*n. Cf. A057771.
%Y A057997 Sequence in context: A006247 A052318 A141309 this_sequence A005273 A103898 
               A140383
%Y A057997 Adjacent sequences: A057994 A057995 A057996 this_sequence A057998 A057999 
               A058000
%K A057997 nonn,hard
%O A057997 1,2
%A A057997 Christian G. Bower (bowerc(AT)usa.net), Nov 20 2000