%I #9 Apr 09 2014 10:13:02
%S 0,1,10,252,12176,966240,114341760,18897709824,4160840140800,
%T 1177736213606400,416807049369600000,180368555623280640000,
%U 93711488655948742656000,57572391079539343687680000
%N a(n)=(2n)!*(sum{k=1...2n}1/k)/(2n+1).
%C Every term is an integer.
%F a(n) = A000254(2n)/(2n+1)
%p seq((2*n)!*(sum(1/k,k=1..2*n))/(2*n+1),n=0..15); - _Emeric Deutsch_, May 15 2006
%t Table[(2n)! Sum[1/k,{k,2n}]/(2n+1),{n,0,20}] (* _Harvey P. Dale_, Aug 27 2012 *)
%Y Cf. A000254.
%K nonn
%O 0,3
%A _Leroy Quet_, Feb 14 2006
%E More terms from _Emeric Deutsch_, May 15 2006