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 A062004 #33 May 24 2022 02:41:58
%S A062004 2,-4,-6,0,-10,12,-14,0,0,20,-22,0,-26,28,30,0,-34,0,-38,0,42,44,-46,
%T A062004 0,0,52,0,0,-58,-60,-62,0,66,68,70,0,-74,76,78,0,-82,-84,-86,0,0,92,
%U A062004 -94,0,0,0,102,0,-106,0,110,0,114,116,-118,0,-122,124,0,0,130,-132,-134,0,138,-140,-142,0,-146,148,0,0,154,-156,-158,0
%N A062004 a(n) = 2*n*mu(n).
%C A062004 a(n)/2 is multiplicative because both mu(n) and n are. - _Mitch Harris_, Jun 09 2005
%C A062004 b(n) = a(n)/a(1) is multiplicative with b(p^1) = -p, b(p^e) = 0 if e > 1. - _David W. Wilson_, Jun 12 2005
%H A062004 Harry J. Smith, <a href="/A062004/b062004.txt">Table of n, a(n) for n = 1..1000</a>
%F A062004 a(n) = 2*A055615(n). - _Michel Marcus_, May 03 2022
%t A062004 Table[MoebiusMu[n]2n,{n,100}] (* _Harvey P. Dale_, May 11 2011 *)
%o A062004 (Magma) [2*n*MoebiusMu(n) : n in [1..100]]; // _G. C. Greubel_, May 03 2022
%o A062004 (SageMath) [2*n*moebius(n) for n in (1..100)] # _G. C. Greubel_, May 03 2022
%Y A062004 Cf. A008683, A055615.
%K A062004 easy,sign
%O A062004 1,1
%A A062004 _Jason Earls_, Jul 04 2001