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 A347249 #9 Jan 30 2022 09:50:56
%S A347249 0,0,0,0,0,0,0,0,-1,0,0,0,0,0,1,0,-1,-1,0,0,1,0,0,0,2,0,0,0,1,1,0,0,1,
%T A347249 -1,1,-1,0,0,1,0,1,1,0,0,1,0,0,0,-2,2,0,0,0,0,0,0,1,1,1,1,0,0,0,0,2,1,
%U A347249 -1,-1,1,1,-1,-1,0,0,3,0,1,1,0,0,-1,1,1,1,1,0,2,0,1,1,1,0,1,0,2,0,-2,-2,1,2
%N A347249 a(n) = A331410(n) - A336361(n).
%C A347249 Terms 0 .. 9 occur for the first time at n = 1, 15, 25, 75, 275, 725, 2175, 3725, 9025, 27075.
%H A347249 Antti Karttunen, <a href="/A347249/b347249.txt">Table of n, a(n) for n = 1..65537</a>
%F A347249 a(n) = A331410(n) - A336361(n).
%F A347249 For all n >= 1, a(n) = a(2*n) = a(A000265(n)).
%o A347249 (PARI)
%o A347249 A331410(n) = { my(f=factor(n)); sum(k=1,#f~,if(2==f[k,1],0,f[k,2]*(1+A331410(f[k,1]+1)))); };
%o A347249 A336361(n) = if(!bitand(n,n-1),0,1+A336361(sigma(n>>valuation(n,2))));
%o A347249 A347249(n) = (A331410(n)-A336361(n));
%Y A347249 Cf. A000265, A331410, A336361, A347250 (positions of negative terms).
%Y A347249 Cf. also A347374.
%K A347249 sign
%O A347249 1,25
%A A347249 _Antti Karttunen_, Aug 28 2021