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%I #11 Jun 01 2014 07:54:11
%S 2,2,2,3,6,15,48,168,840,4536,26880,147840,1209600,7862400,67267200,
%T 648648000,7783776000,66162096000,871782912000,8281937664000,
%U 118562476032000,1680623097753600,23416681828700160,269291841030051840,5109094217170944000
%N a(n)=2*n!/d(n!); d(m)=A000005(m) is the number of divisors of m.
%C a(3)=3 and a(5)=15 are the only odd numbers in this sequence.
%D P. Erdos, solved by J. Fiedler, Elem. Math. 16 (1961), 42-44, Aufgabe 374.
%F a(n)=2*A000142(n)/A027423(n).
%e a(4)=2*4!/d(4!)=2*24/8=6.
%t Table[(2n!)/DivisorSigma[0,n!],{n,0,25}] (* _Harvey P. Dale_, Jun 01 2014 *)
%o (PARI) a(n) = 2*n!/numdiv(n!); \\ _Michel Marcus_, Aug 26 2013
%Y Cf. A000142, A027423.
%K nonn
%O 0,1
%A _Franz Vrabec_, Feb 01 2007
%E More terms from _Michel Marcus_, Aug 26 2013
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