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 A344369 #5 May 16 2021 12:25:34 %S A344369 1,-2,-3,0,-5,0,-7,-8,0,0,-11,0,-13,0,0,16,-17,0,-19,0,0,0,-23,24,0,0, %T A344369 -27,0,-29,30,-31,-32,0,0,0,36,-37,0,0,40,-41,42,-43,0,0,0,-47,0,0,0, %U A344369 0,0,-53,54,0,56,0,0,-59,60,-61,0,0,64,0,66,-67,0,0,70 %N A344369 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(1-s)). %F A344369 a(n) = n * A316441(n). %t A344369 facs[n_] := If[n <= 1, {{}}, Join @@ Table[Map[Prepend[#, d] &, Select[facs[n/d], Min @@ # >= d &]], {d, Rest[Divisors[n]]}]]; A316441[n_] := Sum[(-1)^Length[f], {f, facs[n]}]; Table[n A316441[n], {n, 70}] %Y A344369 Cf. A022693, A224892, A316441, A328731, A344368, A344370. %K A344369 sign %O A344369 1,2 %A A344369 _Ilya Gutkovskiy_, May 16 2021