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 A358679 #7 Dec 23 2022 16:22:29
%S A358679 1,0,-1,0,-1,0,-1,0,0,0,-1,0,-1,0,2,0,-1,0,-1,0,2,0,-1,0,0,0,0,0,-1,0,
%T A358679 -1,0,2,0,2,0,-1,0,2,0,-1,0,-1,0,-1,0,-1,0,0,0,2,0,-1,0,2,0,2,0,-1,0,
%U A358679 -1,0,-1,0,2,0,-1,0,2,0,-1,0,-1,0,-1,0,2,0,-1,0,0,0,-1,0,2,0,2,0,-1,0,2,0,2,0,2,0,-1,0,-1,0,-1,0,-1,0,-6
%N A358679 Dirichlet inverse of the characteristic function of A061345, odd prime powers.
%H A358679 Antti Karttunen, <a href="/A358679/b358679.txt">Table of n, a(n) for n = 1..100000</a>
%F A358679 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A174275(n/d) * a(d).
%o A358679 (PARI)
%o A358679 A174275(n) = ((n%2)&&isprimepower(n));
%o A358679 memoA358679 = Map();
%o A358679 A358679(n) = if(1==n,1,my(v); if(mapisdefined(memoA358679,n,&v), v, v = -sumdiv(n,d,if(d<n,A174275(n/d)*A358679(d),0)); mapput(memoA358679,n,v); (v)));
%Y A358679 Cf. A061345, A174275.
%K A358679 sign
%O A358679 1,15
%A A358679 _Antti Karttunen_, Dec 23 2022