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 A325699 #14 Jun 17 2024 07:14:44
%S A325699 0,-1,1,-1,-1,0,1,-1,1,-2,-1,0,1,0,0,-1,-1,0,1,-2,2,-2,-1,0,-1,0,1,0,
%T A325699 1,-1,-1,-1,0,-2,0,0,1,0,2,-2,-1,1,1,-2,0,-2,-1,0,1,-2,0,0,1,0,-2,0,2,
%U A325699 0,-1,-1,1,-2,2,-1,0,-1,-1,-2,0,-1,1,0,-1,0,0,0
%N A325699 Number of distinct even prime indices of n minus the number of distinct odd prime indices of n.
%C A325699 A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
%F A325699 G.f.: Sum_{k>=1} (-1)^k * x^prime(k) / (1 - x^prime(k)). - _Ilya Gutkovskiy_, Feb 12 2020
%F A325699 Additive with a(p^e) = (-1)^primepi(p). - _Amiram Eldar_, Jun 17 2024
%t A325699 Table[Total[(-1)^PrimePi/@First/@If[n==1,{},FactorInteger[n]]],{n,100}]
%Y A325699 a(n) = A324967(n) - A324966(n).
%Y A325699 Cf. A000712, A001221, A026010, A045931, A063886, A112798, A130780, A171966, A241638, A325698, A325700.
%K A325699 sign
%O A325699 1,10
%A A325699 _Gus Wiseman_, May 17 2019