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%I #17 Nov 23 2024 16:11:54
%S 1,1,1,6,33,75,877,2075,38692,239794,1250340,18495201,43023264,
%T 4554211553,70490483945,911526001064,182477118528,219638126087356,
%U 13070186026272,79249480638985626
%N Number of permutations p of (1,2,3,...,n) such that Sum_{k=1..n} gcd(k,p(k)) = sigma(n).
%o (PARI) a(n)=sum(k=1,n!,if(sum(i=1,n,gcd(i, component(numtoperm(n,k),i)))-sigma(n),0,1))
%K more,nonn
%O 1,4
%A _Benoit Cloitre_, Aug 23 2002
%E a(10) from Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 14 2004
%E a(11) from _Rick L. Shepherd_, Mar 15 2004
%E a(12)-a(13) from _Ryan Propper_, Oct 25 2006
%E a(14)-a(20) from _Robert Gerbicz_, Nov 19 2010