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 A300821 #13 Mar 20 2018 12:04:12
%S A300821 1,-1,2,4,2,-2,0,-4,6,8,8,8,12,12,4,10,8,-6,0,-14,0,-4,2,-8,-2,-12,18,
%T A300821 12,26,16,30,20,16,20,24,24,36,36,24,44,38,24,36,28,12,26,26,20,30,22,
%U A300821 16,24,26,-18,-10,-24,0,-22,2,-28,0,-30,0,-20,-6,-8,12,-20,4,-36,8,-24,0,-36,-4,-36,-6,-24,0,-50,54,44,80,24
%N A300821 Möbius transform of A244042.
%H A300821 Antti Karttunen, <a href="/A300821/b300821.txt">Table of n, a(n) for n = 1..65537</a>
%F A300821 a(n) = Sum_{d|n} moebius(n/d)*A244042(d).
%F A300821 a(n) = A000010(n) - A300822(n).
%F A300821 a(n) = A244042(n) - A300823(n).
%t A300821 Table[DivisorSum[n, MoebiusMu[n/#] FromDigits[IntegerDigits[#, 3] /. 2 -> 0, 3] &], {n, 84}] (* _Michael De Vlieger_, Mar 17 2018 *)
%o A300821 (PARI)
%o A300821 A244042(n) = fromdigits(apply(x->(x%2), digits(n, 3)), 3);
%o A300821 A300821(n) = sumdiv(n,d,moebius(n/d)*A244042(d));
%Y A300821 Cf. A000010, A244042, A300822, A300823.
%K A300821 sign,base,look
%O A300821 1,3
%A A300821 _Antti Karttunen_, Mar 14 2018