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 A073318 #15 Jan 23 2021 23:37:30
%S A073318 0,-1,-2,-3,-6,-4,-10,-13,-26,-14,-183,-15,-22,-57,-210,-211,-1730,
%T A073318 -58,25160,-240,-3356,-949,238031,-241,-256823,-3918,-143243,-3919,
%U A073318 46326924,-242,281620682,-61817,-639769,-61818,-4718174,-4415,2023569890,-224436,-7556927,-63639,-43279525745,-4416
%N A073318 a(n) = 2^phi(n) - Sum_{j=0..n} binomial(phi(n), phi(j)).
%C A073318 a(n) > 0 for {19, 23, 29, 31, 37, 43, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97}. Does this hold only for special primes?
%C A073318 No: composites for which a(n) > 0 include 121, 289, 437, 529, 667, 671, 697, 703, 713, 731, .... - _Robert Israel_, Jan 23 2021
%H A073318 Robert Israel, <a href="/A073318/b073318.txt">Table of n, a(n) for n = 1..3322</a>
%F A073318 a(n) = A066781(n) - A073317(n).
%t A073318 g[x_] := EulerPhi[x] Table[Apply[Plus, Table[Binomial[g[n], g[j]], {j, 0, n}]], {n, 1, 50}]
%Y A073318 Cf. A066781, A073318.
%K A073318 easy,sign
%O A073318 1,3
%A A073318 _Labos Elemer_, Jul 26 2002