cp's OEIS Frontend

A104529 Denominator of Sum_{k=1..n} 1/tau(k), where tau(k) is the number of divisors function.

%I A104529 #4 Dec 18 2012 08:39:58
%S A104529 1,2,1,3,6,12,12,6,6,12,12,12,12,6,12,60,60,20,20,60,15,60,60,120,40,
%T A104529 40,40,120,120,30,15,30,60,15,60,180,180,45,180,360,360,45,90,45,90,
%U A104529 180,180,180,180,180,90,45,90,360,360,45,180,90,45,180,180,90,45,315,1260
%N A104529 Denominator of Sum_{k=1..n} 1/tau(k), where tau(k) is the number of divisors function.
%H A104529 Harvey P. Dale, <a href="/A104529/b104529.txt">Table of n, a(n) for n = 1..1000</a>
%e A104529 1,3/2,2,7/3,17/6
%e A104529 a(4)=3 because 1/tau(1)+1/tau(2)+1/tau(3)+1/tau(4)=1/1+1/2+1/2+1/3=7/3.
%p A104529 with(numtheory): a:=n->denom(sum(1/tau(k),k=1..n)): seq(a(n),n=1..70);
%t A104529 Denominator[Accumulate[1/#&/@DivisorSigma[0,Range[70]]]] (* _Harvey P. Dale_, Dec 18 2012 *)
%Y A104529 Cf. A104528.
%K A104529 frac,nonn
%O A104529 1,2
%A A104529 _Emeric Deutsch_, Mar 12 2005