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 A304819 #11 Aug 23 2018 02:21:12
%S A304819 1,0,0,0,0,0,0,0,0,0,0,-1,0,0,0,0,0,-1,0,-1,0,0,0,0,0,0,0,-1,0,0,0,0,
%T A304819 0,0,0,-2,0,0,0,0,0,0,0,-1,-1,0,0,-1,0,-1,0,-1,0,0,0,0,0,0,0,-1,0,0,
%U A304819 -1,0,0,0,0,-1,0,0,0,-2,0,0,-1,-1,0,0,0,-1,0
%N A304819 Dirichlet convolution of r with zeta, where r(n) = (-1)^Omega(n) if n is 1 or not a perfect power and r(n) = 0 otherwise.
%C A304819 Omega(n) = A001222(n) is the number of prime factors of n counted with multiplicity.
%H A304819 Antti Karttunen, <a href="/A304819/b304819.txt">Table of n, a(n) for n = 1..65537</a>
%F A304819 a(n) = Sum_{d|n, d = 1 or not a perfect power} (-1)^Omega(d).
%t A304819 Table[Sum[(-1)^PrimeOmega[d],{d,Select[Divisors[n],GCD@@FactorInteger[#][[All,2]]==1&]}],{n,100}]
%o A304819 (PARI) A304819(n) = sumdiv(n,d,if(!ispower(d),(-1)^bigomega(d),0)); \\ _Antti Karttunen_, Jul 29 2018
%Y A304819 Positions of nonzero entries appear to be A126706.
%Y A304819 Cf. A000005, A000007, A001222, A001597, A005117, A007916, A008683, A008836, A304362, A304653, A304779, A304817, A304820.
%K A304819 sign
%O A304819 1,36
%A A304819 _Gus Wiseman_, May 19 2018