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 A355817 #15 Jul 21 2022 16:16:11
%S A355817 1,-1,-1,0,-1,2,-1,0,0,2,-1,-1,-1,2,2,0,-1,-1,-1,-1,2,2,-1,0,0,2,0,-1,
%T A355817 -1,-6,-1,0,2,2,2,2,-1,2,2,0,-1,-6,-1,-1,-1,2,-1,0,0,-1,2,-1,-1,0,2,0,
%U A355817 2,2,-1,6,-1,2,-1,0,2,-6,-1,-1,2,-6,-1,-1,-1,2,-1,-1,2,-6,-1,0,0,2,-1,6,2,2,2,0,-1,6,2
%N A355817 Dirichlet inverse of A010055, characteristic function of powers of primes.
%C A355817 Question: Are the absolute values of this sequence given by A335452? Compare also to A355939 and A008480.
%H A355817 Antti Karttunen, <a href="/A355817/b355817.txt">Table of n, a(n) for n = 1..100000</a>
%H A355817 <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>
%F A355817 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A010055(n/d) * a(d).
%t A355817 s[n_] := If[PrimeNu[n] < 2, 1, 0]; a[1] = 1; a[n_] := a[n] = -DivisorSum[n, s[n/#]*a[#] &, # < n &]; Array[a, 100] (* _Amiram Eldar_, Jul 19 2022 *)
%o A355817 (PARI)
%o A355817 A010055(n) = ((1==n)||isprimepower(n));
%o A355817 memoA355817 = Map();
%o A355817 A355817(n) = if(1==n,1,my(v); if(mapisdefined(memoA355817,n,&v), v, v = -sumdiv(n,d,if(d<n,A010055(n/d)*A355817(d),0)); mapput(memoA355817,n,v); (v)));
%Y A355817 Cf. A010055, A335452.
%Y A355817 Cf. also A050363, A355827, A355939.
%K A355817 sign
%O A355817 1,6
%A A355817 _Antti Karttunen_, Jul 19 2022