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 A357817 #15 Feb 29 2024 13:30:30
%S A357817 1,-2,2,-4,2,-10,-2,-14,-2,-20,-8,-32,-18,-42,-18,-42,-24,-60,-40,-76,
%T A357817 -44,-80,-56,-104,-74,-116,-80,-128,-98,-170,-138,-186,-138,-192,-144,
%U A357817 -216,-178,-238,-182,-254,-212,-308,-264,-336,-264,-336,-288,-384,-328,-418
%N A357817 Partial alternating sums of the Dedekind psi function (A001615): a(n) = Sum_{k=1..n} (-1)^(k+1) * psi(k).
%H A357817 Amiram Eldar, <a href="/A357817/b357817.txt">Table of n, a(n) for n = 1..10000</a>
%H A357817 László Tóth, <a href="https://www.emis.de/journals/JIS/VOL20/Toth/toth25.html">Alternating Sums Concerning Multiplicative Arithmetic Functions</a>, Journal of Integer Sequences, Vol. 20 (2017), Article 17.2.1.
%F A357817 a(n) = -(3/(2*Pi^3)) * n^2 + O(n * log(n)^(2/3)) (Tóth, 2017).
%t A357817 psi[n_] := n * Times @@ (1 + 1/Transpose[FactorInteger[n]][[1]]); psi[1] = 1; Accumulate[Array[(-1)^(# + 1)*psi[#] &, 50]]
%o A357817 (PARI) f(n) = n * sumdivmult(n, d, issquarefree(d)/d); \\ A001615
%o A357817 a(n) = sum(k=1, n, (-1)^(k+1) * f(k)); \\ _Michel Marcus_, Oct 15 2022
%Y A357817 Cf. A001615, A173290.
%Y A357817 Similar sequences: A068762, A068773, A307704.
%K A357817 sign
%O A357817 1,2
%A A357817 _Amiram Eldar_, Oct 14 2022