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 A378445 #7 Nov 27 2024 17:56:18
%S A378445 0,1,1,2,1,3,1,3,1,3,1,4,1,3,2,3,1,4,1,4,2,3,1,6,1,3,2,4,1,6,1,4,2,3,
%T A378445 2,6,1,3,2,6,1,6,1,4,3,3,1,7,1,4,2,4,1,6,2,6,2,3,1,8,1,3,3,5,2,6,1,4,
%U A378445 2,6,1,9,1,3,3,4,2,6,1,7,2,3,1,8,2,3,2,6,1,9,2,4,2,3,2,9,1,4,3,6,1,6,1,6,4
%N A378445 a(n) is the number of divisors d of n such that A083345(d) is odd, where A083345(n) is the numerator of Sum(e/p: n=Product(p^e)).
%C A378445 Number of terms of A369003 that divide n.
%H A378445 Antti Karttunen, <a href="/A378445/b378445.txt">Table of n, a(n) for n = 1..65537</a>
%F A378445 a(n) = Sum_{d|n} A377874(d).
%F A378445 a(n) = A000005(n) - A378444(n).
%o A378445 (PARI)
%o A378445 A377874(n) = { my(f=factor(n)); (numerator(vecsum(vector(#f~, i, f[i, 2]/f[i, 1])))%2); };
%o A378445 A378445(n) = sumdiv(n,d,A377874(d));
%Y A378445 Inverse Möbius transform of A377874.
%Y A378445 Cf. A000005, A369003, A378444.
%Y A378445 Cf. also A174273, A378443.
%K A378445 nonn
%O A378445 1,4
%A A378445 _Antti Karttunen_, Nov 27 2024