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%I #27 Apr 03 2023 07:44:10
%S 1,1,3,33,825,113025,5538225,60920475,46360481475,330503872435275,
%T 20160736218551775,1687675389591187637025,145175524688023551724527525,
%U 166370135063802174111446471957325,194941377468714112878127508925972294225
%N Denominator of Sum_{k=1..n} 1/H(k), where H(k) = Sum_{j=1..k} 1/j is the k-th harmonic number.
%C If p > 3 is prime, then p^2 divides a(p-1). - _Thomas Ordowski_, Mar 24 2023
%t f[n_] := Denominator[ Sum[ 1/HarmonicNumber[j], {j, n}]]; Table[ f[n], {n, 0, 14}] (* _Ray Chandler_, Dec 16 2006 *)
%o (PARI) a(n) = denominator(sum(k=1, n, 1/sum(j=1, k, 1/j))); \\ _Michel Marcus_, Mar 24 2023
%Y Cf. A096987 (numerators), A001008, A002805.
%K frac,nonn
%O 0,3
%A _Leroy Quet_, Dec 15 2006
%E Extended by _Ray Chandler_ and _Robert G. Wilson v_, Dec 16 2006
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