Search: id:A125721
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%I A125721
%S A125721 2,2,2,3,6,15,48,168,840,4536,26880,147840,1209600
%N A125721 a(n)=2*n!/d(n!); d(m)=A000005(m) is the number of divisors of m.
%C A125721 a(3)=3 and a(5)=15 are the only odd numbers in this sequence.
%D A125721 P. Erdos, solved by J. Fiedler, Elem. Math. 16 (1961), 42-44, Aufgabe 
               374.
%F A125721 a(n)=2*A000142(n)/A027423(n).
%e A125721 a(4)=2*4!/d(4!)=2*24/8=6.
%Y A125721 Cf. A000142, A027423.
%Y A125721 Sequence in context: A147851 A143596 A091712 this_sequence A049798 A165198 
               A024682
%Y A125721 Adjacent sequences: A125718 A125719 A125720 this_sequence A125722 A125723 
               A125724
%K A125721 nonn
%O A125721 0,1
%A A125721 Franz Vrabec (franz.vrabec(AT)aon.at), Feb 01 2007

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