%I #7 Jun 19 2023 16:52:49

%S 1,4,35,257,11,271,183,2773,36329,109897,110443,27757,55709,37291,

%T 49873,1549703,13975537,14010257,2806565,2811401,5631265,9400487,

%U 103518197,103642321,103738417,311569891,311818139,312084119,312296903,312607213

%N Numerator of sum(1/(phi(k)sigma(k)),k=1..n), where phi(k) is the totient function and sigma(k) is the sum of the divisors function.

%C The first 5 sums are: 1,4/3,35/24,257/168,11/7.

%H Harvey P. Dale, <a href="/A104526/b104526.txt">Table of n, a(n) for n = 1..1000</a>

%e a(3)=35 because phi(1)*sigma(1)+phi(2)*sigma(2)+phi(3)*sigma(3)=1/(1*1)+1/(1*3)+1/(2*4)=35/24.

%p with(numtheory): a:=n->numer(sum(1/phi(k)/sigma(k),k=1..n)): seq(a(n),n=1..35);

%t Accumulate[Table[1/(EulerPhi[n]DivisorSigma[1,n]),{n,30}]]//Numerator (* _Harvey P. Dale_, Jun 19 2023 *)

%Y Cf. A104527, A093827.

%K frac,nonn

%O 1,2

%A _Emeric Deutsch_, Mar 12 2005