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 A351394 #18 Oct 06 2023 10:54:11
%S A351394 1,2,2,3,2,4,2,4,3,4,2,5,2,4,4,5,2,5,2,5,4,4,2,6,3,4,4,5,2,8,2,6,4,4,
%T A351394 4,6,2,4,4,6,2,8,2,5,5,4,2,7,3,5,4,5,2,6,4,6,4,4,2,9,2,4,5,7,4,8,2,5,
%U A351394 4,8,2,7,2,4,5,5,4,8,2,7,5,4,2,9,4,4,4,6,2,9,4,5,4,4,4
%N A351394 Number of divisors of n that are either squarefree, prime powers, or both.
%H A351394 Amiram Eldar, <a href="/A351394/b351394.txt">Table of n, a(n) for n = 1..10000</a>
%H A351394 <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>
%F A351394 a(n) = Sum_{d|n} sign(mu(d)^2 + [omega(d) = 1]).
%F A351394 a(n) = Sum_{d|n} (mu(d)^2 + [omega(d) = 1]*(1 - mu(d)^2)).
%F A351394 a(n) = A048105(n) + A046660(n). - _Amiram Eldar_, Oct 06 2023
%e A351394 a(36) = 6; 36 has 4 squarefree divisors 1,2,3,6 (where the primes 2 and 3 are both squarefree and 1st powers of primes) and 2 (additional) divisors that are powers of primes, 2^2 and 3^2.
%t A351394 a[n_] := Module[{e = FactorInteger[n][[;;, 2]], nu, omega}, nu = Length[e]; omega = Total[e]; 2^nu + omega - nu]; a[1] = 1; Array[a, 100] (* _Amiram Eldar_, Oct 06 2023 *)
%o A351394 (PARI) a(n) = {my(f = factor(n), nu = omega(f), om = bigomega(f)); 2^nu + om - nu;} \\ _Amiram Eldar_, Oct 06 2023
%Y A351394 Cf. A001221, A008683, A046660, A048105, A246655.
%Y A351394 Cf. Similar to A327527.
%K A351394 nonn,easy
%O A351394 1,2
%A A351394 _Wesley Ivan Hurt_, Feb 09 2022