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 A369258 #9 Jan 24 2024 21:27:06
%S A369258 0,0,1,0,1,1,1,0,1,1,1,1,1,1,2,0,1,1,1,1,2,1,1,1,1,1,2,1,1,2,1,0,2,1,
%T A369258 2,1,1,1,2,1,1,2,1,1,3,1,1,1,1,1,2,1,1,2,2,1,2,1,1,2,1,1,3,0,2,2,1,1,
%U A369258 2,2,1,1,1,1,3,1,2,2,1,1,2,1,1,2,2,1,2,1,1,3,2,1,2,1,2,1,1,1,3,1,1,2,1,1,4
%N A369258 a(n) = number of odd divisors of n that have an odd number of prime factors with multiplicity.
%H A369258 Antti Karttunen, <a href="/A369258/b369258.txt">Table of n, a(n) for n = 1..65537</a>
%F A369258 a(n) = Sum_{d|n} A353558(d).
%F A369258 a(n) = A001227(n) - A369257(n).
%e A369258 Of the eight odd divisors of 105, the four divisors 3, 5, 7, 105 all have an odd number of prime factors (A001222(d) is odd), therefore a(105) = 4.
%t A369258 Array[DivisorSum[#, 1 &, And[OddQ[#], OddQ@ PrimeOmega[#]] &] &, 120] (* _Michael De Vlieger_, Jan 24 2024 *)
%o A369258 (PARI)
%o A369258 A353558(n) = ((n%2)&&(bigomega(n)%2));
%o A369258 A369258(n) = sumdiv(n,d,A353558(d));
%Y A369258 Inverse Möbius transform of A353558.
%Y A369258 Cf. A001227, A067019, A369257.
%K A369258 nonn
%O A369258 1,15
%A A369258 _Antti Karttunen_, Jan 24 2024