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 A378224 #8 Nov 25 2024 16:34:57
%S A378224 1,-1,-2,-1,-2,0,-2,-1,0,0,-2,0,-2,0,2,-1,-2,0,-2,0,2,0,-2,0,0,0,0,0,
%T A378224 -2,0,-2,-1,2,0,2,0,-2,0,2,0,-2,0,-2,0,0,0,-2,0,0,0,2,0,-2,0,2,0,2,0,
%U A378224 -2,0,-2,0,0,-1,2,0,-2,0,2,0,-2,0,-2,0,0,0,2,0,-2,0,0,0,-2,0,2,0,2,0,-2,0,2,0,2,0,2,0,-2
%N A378224 Dirichlet inverse of A378223.
%C A378224 Möbius transform of A378218.
%H A378224 Antti Karttunen, <a href="/A378224/b378224.txt">Table of n, a(n) for n = 1..65537</a>
%F A378224 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A378223(n/d) * a(d).
%F A378224 a(n) = Sum_{d|n} A008683(n/d)*A378218(d).
%o A378224 (PARI)
%o A378224 memoA345182 = Map();
%o A378224 A345182(n) = if(n<=2, n%2, my(v); if(mapisdefined(memoA345182,n,&v), v, v = sumdiv(n,d,if(d<n,A345182(d),0)); mapput(memoA345182,n,v); (v)));
%o A378224 A378223(n) = sumdiv(n,d,A345182(d));
%o A378224 memoA378224 = Map();
%o A378224 A378224(n) = if(1==n,1,my(v); if(mapisdefined(memoA378224,n,&v), v, v = -sumdiv(n,d,if(d<n,A378223(n/d)*A378224(d),0)); mapput(memoA378224,n,v); (v)));
%Y A378224 Cf. A008683, A345182, A378218, A378223.
%Y A378224 Cf. also A378225.
%K A378224 sign
%O A378224 1,3
%A A378224 _Antti Karttunen_, Nov 25 2024