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A114450 a(n)=(2n)!*(sum{k=1...2n}1/k)/(2n+1). 1

%I

%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

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Last modified December 18 16:37 EST 2018. Contains 318229 sequences. (Running on oeis4.)