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 A378211 #6 Nov 22 2024 13:31:53
%S A378211 1,-4,-5,4,-7,18,-9,0,6,26,-13,-16,-15,34,33,0,-19,-18,-21,-24,43,50,
%T A378211 -25,0,10,58,0,-32,-31,-114,-33,0,63,74,61,12,-39,82,73,0,-43,-150,
%U A378211 -45,-48,-36,98,-49,0,14,-30,93,-56,-55,0,89,0,103,122,-61,96,-63,130,-48,0,103,-222,-69,-72,123,-218,-73,0,-75
%N A378211 Dirichlet inverse of A191161, hypersigma variant 2.
%H A378211 Antti Karttunen, <a href="/A378211/b378211.txt">Table of n, a(n) for n = 1..20000</a>
%F A378211 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A191161(n/d) * a(d).
%o A378211 (PARI)
%o A378211 A191161(n) = sumdiv(n, d, if(d<n, d+A191161(d), n));
%o A378211 memoA378211 = Map();
%o A378211 A378211(n) = if(1==n,1,my(v); if(mapisdefined(memoA378211,n,&v), v, v = -sumdiv(n,d,if(d<n,A191161(n/d)*A378211(d),0)); mapput(memoA378211,n,v); (v)));
%Y A378211 Cf. A191161.
%Y A378211 Cf. also A378210.
%K A378211 sign
%O A378211 1,2
%A A378211 _Antti Karttunen_, Nov 22 2024