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Denominator of sum_{k=1..n} 1/(k*H(k)) where H(k) is the harmonic number H(k) = sum_{j=1..n} 1/j.
1

%I #7 Dec 31 2013 02:56:24

%S 1,1,3,33,825,113025,5538225,60920475,46360481475,330503872435275,

%T 20160736218551775,1687675389591187637025,145175524688023551724527525,

%U 166370135063802174111446471957325,194941377468714112878127508925972294225,8038017817167489016303831575544615607779425

%N Denominator of sum_{k=1..n} 1/(k*H(k)) where H(k) is the harmonic number H(k) = sum_{j=1..n} 1/j.

%C The corresponding numerators are in A234714.

%C A124432(n) = a(n) for 0 <= n <= 53, but A124432(54) = 3 * a(54).

%t nmax = 54; Table[ Denominator[ Sum[ 1/(k HarmonicNumber[k]), {k, 1, n} ] ], {n, 0, nmax} ]

%Y Cf. A001008, A002805, A000254, A096987, A124432, A234714

%K nonn,easy

%O 0,3

%A _Stuart Clary_, Dec 29 2013