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 A366789 #10 Oct 23 2023 15:07:16
%S A366789 1,1,1,1,3,1,1,1,1,3,5,1,3,1,3,1,7,1,1,3,1,5,9,1,9,3,1,1,5,3,11,1,5,7,
%T A366789 3,1,3,1,3,3,13,1,7,5,3,9,15,1,1,9,7,3,1,1,15,1,1,5,17,3,9,11,1,1,9,5,
%U A366789 19,7,9,3,5,1,21,3,9,1,5,3,11,3,1,13,23,1,21,7,5,5,3,3,3,9,11,15,3,1,25,1,5,9
%N A366789 Fully multiplicative with a(p) = oddpart(primepi(p)).
%H A366789 Antti Karttunen, <a href="/A366789/b366789.txt">Table of n, a(n) for n = 1..52711</a>
%H A366789 <a href="/index/Pri#prime_indices">Index entries for sequences related to prime indices in the factorization of n</a>
%F A366789 a(n) = A000265(A003963(n)).
%t A366789 {1}~Join~Array[#/2^IntegerExponent[#, 2] &@ Apply[Times, PrimePi[#1]^#2 & @@@ FactorInteger[#]] &, 120, 2] (* _Michael De Vlieger_, Oct 23 2023 *)
%o A366789 (PARI)
%o A366789 A000265(n) = (n>>valuation(n,2));
%o A366789 A366789(n) = { my(f=factor(n)); prod(k=1, #f~, A000265(primepi(f[k, 1]))^f[k, 2]); };
%Y A366789 Cf. A000265, A000720, A003963, A366790.
%Y A366789 Cf. also A336466.
%K A366789 nonn,mult
%O A366789 1,5
%A A366789 _Antti Karttunen_, Oct 23 2023