This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A079536 #11 Sep 08 2022 08:45:08
%S A079536 0,-1,0,-1,2,-4,4,1,5,-2,8,-4,10,0,8,9,14,-3,16,6,16,4,20,4,29,6,32,
%T A079536 16,26,-8,28,33,32,10,48,17,34,12,40,38,38,0,40,36,66,16,44,36,69,27,
%U A079536 56,46,50,24,88,72,64,22,56,24,58,24,112,97,108,16,64,66,80,48,68,93,70,30,116,76,144
%N A079536 a(n) = phi(n)*d(n) - sigma(n).
%C A079536 It is known that a(n) >= 0 if n is odd
%D A079536 D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 10.
%H A079536 G. C. Greubel, <a href="/A079536/b079536.txt">Table of n, a(n) for n = 1..10000</a>
%t A079536 Table[EulerPhi[n]*DivisorSigma[0, n] - DivisorSigma[1, n], {n,1,80}] (* _G. C. Greubel_, Jan 14 2019 *)
%o A079536 (PARI) vector(80, n, eulerphi(n)*sigma(n,0) - sigma(n,1)) \\ _G. C. Greubel_, Jan 14 2019
%o A079536 (Magma) [EulerPhi(n)*DivisorSigma(0,n) - DivisorSigma(1,n): n in [1..80]]; // _G. C. Greubel_, Jan 14 2019
%o A079536 (Sage) [euler_phi(n)*sigma(n, 0) - sigma(n,1) for n in (1..80)] # _G. C. Greubel_, Jan 14 2019
%Y A079536 Cf. A000010, A000005, A000203, A062355, A079535, A079537.
%K A079536 sign
%O A079536 1,5
%A A079536 _N. J. A. Sloane_, Jan 23 2003