A348510 - OEIS

%I #12 Nov 24 2021 18:18:56

%S 0,2,0,8,0,-4,0,24,18,10,0,6,0,-7,-10,64,0,18,0,0,0,0,0,-8,50,26,0,

%T -25,0,-20,0,32,-22,34,0,288,0,0,0,-8,0,-35,0,-22,0,-23,0,72,0,50,-34,

%U 104,0,-36,0,0,0,58,0,-30,0,-31,126,384,0,-55,0,0,-46,-35,0,216,0,74,150,38,0,-52,0,320,324,82,0,-75

%N a(n) = A099377(n) - n, where A099377(n) is the numerator of the harmonic mean of the divisors of n.

%H Antti Karttunen, <a href="/A348510/b348510.txt">Table of n, a(n) for n = 1..20000</a>

%t a[n_] := Numerator[DivisorSigma[0, n]/DivisorSigma[-1, n]] - n; Array[a, 100] (* _Amiram Eldar_, Oct 31 2021 *)

%o (PARI)

%o A099377(n) = { my(d=divisors(n)); numerator(#d/sum(k=1, #d, 1/d[k])); }; \\  From A099377

%o A348510(n) = (A099377(n)-n);

%Y Cf. A099377, A250094 (positions of zeros), A348968, A348969.

%K sign

%O 1,2

%A _Antti Karttunen_, Oct 31 2021