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 A378453 #7 Nov 29 2024 21:04:50
%S A378453 1,-2,-2,1,-2,3,-2,0,1,3,-2,0,-2,3,3,0,-2,0,-2,0,3,3,-2,-1,1,3,0,0,-2,
%T A378453 -2,-2,0,3,3,3,-2,-2,3,3,-1,-2,-2,-2,0,0,3,-2,0,1,0,3,0,-2,-1,3,-1,3,
%U A378453 3,-2,-3,-2,3,0,0,3,-2,-2,0,3,-2,-2,0,-2,3,0,0,3,-2,-2,0,0,3,-2,-3,3,3,3,-1,-2,-3,3,0,3,3,3
%N A378453 Dirichlet inverse of A018892, where A018892(n) = (tau(n^2)+1)/2.
%C A378453 Möbius transform of A378452.
%H A378453 Antti Karttunen, <a href="/A378453/b378453.txt">Table of n, a(n) for n = 1..20000</a>
%F A378453 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A018892(n/d) * a(d).
%F A378453 a(n) = Sum_{d|n} A008683(n/d)*A378452(d).
%o A378453 (PARI)
%o A378453 A018892(n) = ((numdiv(n^2)+1)/2);
%o A378453 memoA378453 = Map();
%o A378453 A378453(n) = if(1==n,1,my(v); if(mapisdefined(memoA378453,n,&v), v, v = -sumdiv(n,d,if(d<n,A018892(n/d)*A378453(d),0)); mapput(memoA378453,n,v); (v)));
%Y A378453 Cf. A008683, A018892, A378452.
%K A378453 sign
%O A378453 1,2
%A A378453 _Antti Karttunen_, Nov 29 2024