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 A378438 #7 Nov 26 2024 20:59:39
%S A378438 1,-2,-2,1,-2,3,-2,0,1,4,-2,-1,-2,4,4,0,-2,-1,-2,-3,4,4,-2,-2,1,4,0,
%T A378438 -3,-2,-8,-2,0,4,4,4,-2,-2,4,4,0,-2,-7,-2,-2,-2,4,-2,0,1,-2,4,-2,-2,0,
%U A378438 4,1,4,4,-2,-21,-2,4,-2,0,4,-7,-2,-2,4,-8,-2,-10,-2,4,-2,-2,4,-6,-2,0,0,4,-2,-15,4,4,4,-1,-2
%N A378438 Dirichlet inverse of A378436, where A378436 is the inverse Möbius transform of the number of partitions of n into distinct divisors of n.
%C A378438 Equivalently, Möbius transform of the Dirichlet inverse of A033630.
%H A378438 Antti Karttunen, <a href="/A378438/b378438.txt">Table of n, a(n) for n = 1..20000</a>
%F A378438 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A378436(n/d) * a(d).
%F A378438 a(n) = Sum_{d|n} A008683(n/d)*A378437(d).
%o A378438 (PARI)
%o A378438 A033630(n) = if(!n, 1, my(p=1); fordiv(n, d, p *= (1 + 'x^d)); polcoeff(p, n));
%o A378438 A378436(n) = sumdiv(n,d,A033630(d));
%o A378438 memoA378438 = Map();
%o A378438 A378438(n) = if(1==n,1,my(v); if(mapisdefined(memoA378438,n,&v), v, v = -sumdiv(n,d,if(d<n,A378436(n/d)*A378438(d),0)); mapput(memoA378438,n,v); (v)));
%Y A378438 Cf. A008683, A033630.
%Y A378438 Dirichlet inverse of A378436.
%Y A378438 Möbius transform of A378437.
%K A378438 sign
%O A378438 1,2
%A A378438 _Antti Karttunen_, Nov 26 2024