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 A361985 #15 May 10 2023 04:31:33
%S A361985 1,1,-3,6,-5,-3,-7,24,0,-5,-11,-18,-13,-7,15,96,-17,0,-19,-30,21,-11,
%T A361985 -23,-72,0,-13,0,-42,-29,15,-31,384,33,-17,35,0,-37,-19,39,-120,-41,
%U A361985 21,-43,-66,0,-23,-47,-288,0,0,51,-78,-53,0,55,-168,57,-29,-59,90,-61,-31,0,1536,65,33,-67,-102,69,35,-71,0,-73,-37,0
%N A361985 a(1) = 1, a(2) = 1; a(n) = n * Sum_{d|n, d < n} (-1)^(n/d) a(d) / d.
%H A361985 Seiichi Manyama, <a href="/A361985/b361985.txt">Table of n, a(n) for n = 1..10000</a>
%F A361985 a(n) is multiplicative with a(2) = 1, a(2^e) = 6*4^(e-2) if e>1. a(p) = -p, a(p^e) = 0 if e>1, p>2.
%F A361985 G.f. A(x) satisfies -x * (1 - x) = Sum_{k>=1} (-1)^k * k * A(x^k).
%t A361985 f[p_, e_] := If[e == 1, -p, 0]; f[2, e_] := If[e == 1, 1, 6*4^(e-2)]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* _Amiram Eldar_, May 09 2023 *)
%Y A361985 Partial sums give A359479.
%Y A361985 Cf. A361984, A361986.
%Y A361985 Cf. A359484.
%K A361985 sign,mult
%O A361985 1,3
%A A361985 _Seiichi Manyama_, Apr 02 2023