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 A062816 #22 Jul 10 2024 02:57:30
%S A062816 -1,-2,-2,-2,-2,-4,-2,0,0,-4,-2,0,-2,-4,2,8,-2,0,-2,8,6,-4,-2,16,10,
%T A062816 -4,18,16,-2,4,-2,32,14,-4,26,36,-2,-4,18,48,-2,12,-2,32,54,-4,-2,64,
%U A062816 28,20,26,40,-2,36,50,80,30,-4,-2,72,-2,-4,90,96,62,28,-2,56,38,52,-2,144,-2,-4,90,64,86,36,-2,160,108,-4,-2,120,86,-4
%N A062816 a(n) = phi(n)*tau(n) - 2n = A000010(n)*A000005(n) - 2*n.
%C A062816 It can be shown that phi(n)*tau(n) >= n, which means that quotient = n/tau(n) <= phi(n); note: a(n)+5 is positive.
%C A062816 The value is always positive except when a(n) = 0 for {8,9,12}; or a(n) = -2 for primes together with 4 (i.e., for A046022 but without 1); or a(n) = -4 for A001747 (without 2 and 4); or a(n) = -1 for n = 1.
%H A062816 Harry J. Smith, <a href="/A062816/b062816.txt">Table of n, a(n) for n = 1..2000</a>
%F A062816 a(n) = A062355(n) - 2*n. - _Amiram Eldar_, Jul 10 2024
%t A062816 Table[EulerPhi[n]DivisorSigma[0,n]-2n,{n,90}] (* _Harvey P. Dale_, Feb 03 2021 *)
%o A062816 (PARI) a(n)={eulerphi(n)*numdiv(n) - 2*n} \\ _Harry J. Smith_, Aug 11 2009
%Y A062816 Cf. A000010, A000005, A062355, A062516, A046022, A001747, A036762, A036763, A051728, A051729, A051730.
%K A062816 sign
%O A062816 1,2
%A A062816 _Labos Elemer_, Jul 20 2001
%E A062816 Offset changed from 0 to 1 by _Harry J. Smith_, Aug 11 2009