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A116693 Number of fixed-point-free subgroups of the symmetric group S_n.

%I A116693 #17 Dec 17 2019 12:04:08
%S A116693 1,0,1,2,15,50,874,3515,94638,634630,18368060,149965474,7392944314,
%T A116693 61596293433,4042125261152,46326163964879,4045711099761347,
%U A116693 47868661342996788,6066544790946772416
%N A116693 Number of fixed-point-free subgroups of the symmetric group S_n.
%H A116693 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%t A116693 A005432 = Cases[Import["https://oeis.org/A005432/b005432.txt", "Table"], {_, _}][[All, 2]];
%t A116693 a[n_] := Sum[(-1)^(n-k) Binomial[n, k] A005432[[k+1]], {k, 0, n}];
%t A116693 a /@ Range[0, Length[A005432]-1] (* _Jean-François Alcover_, Dec 17 2019 *)
%Y A116693 Labeled version of A000637. Inverse binomial Transform of A005432.
%K A116693 nonn,hard
%O A116693 0,4
%A A116693 _Christian G. Bower_, Feb 23 2006
%E A116693 More terms from inverse binomial transform of A005432 by _R. J. Mathar_, Mar 03 2015