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 A378216 #15 Nov 23 2024 10:45:09
%S A378216 1,0,0,-1,0,-2,0,-2,-1,-2,0,-4,0,-2,-2,-3,0,-4,0,-4,-2,-2,0,-6,-1,-2,
%T A378216 -2,-4,0,-6,0,-4,-2,-2,-2,-7,0,-2,-2,-6,0,-6,0,-4,-4,-2,0,-8,-1,-4,-2,
%U A378216 -4,0,-6,-2,-6,-2,-2,0,-10,0,-2,-4,-5,-2,-6,0,-4,-2,-6,0,-10,0,-2,-4,-4,-2,-6,0,-8,-3,-2,0,-10
%N A378216 Dirichlet inverse of A174725.
%H A378216 Antti Karttunen, <a href="/A378216/b378216.txt">Table of n, a(n) for n = 1..65537</a>
%F A378216 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A174725(n/d) * a(d).
%F A378216 For n > 1, a(n) = -A070824(n) = 2-A000005(n).
%F A378216 a(n) = Sum_{d|n} A023900(d) * A033879(n/d) = Sum_{d|n} A378220(d) * A344587(n/d).
%o A378216 (PARI) A378216(n) = if(1==n,n,2-numdiv(n));
%Y A378216 Cf. A000005, A070824, A174725.
%Y A378216 Cf. A023900, A033879, A344587, A378220.
%K A378216 sign
%O A378216 1,6
%A A378216 _Antti Karttunen_, Nov 22 2024