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 A386574 #5 Jul 26 2025 22:51:08
%S A386574 1,2,2,2,1,4,1,2,2,2,1,4,1,3,3,2,1,4,1,2,2,2,1,4,1,2,2,3,1,6,1,2,2,2,
%T A386574 2,4,1,2,2,2,1,6,1,2,3,2,1,4,1,2,2,2,1,4,1,3,2,2,1,6,1,2,2,2,1,4,1,2,
%U A386574 2,5,1,4,1,2,3,2,1,5,1,2,2,2,1,6,1,2,2,2,1,6,1,2,2,2,1,4,1,3,2,2
%N A386574 Number of squarefree balanced divisors of n.
%C A386574 Inverse Möbius transform of c(n) * mu(n)^2, where c = A351114.
%F A386574 a(n) = Sum_{d|n} c(d) * mu(d)^2, where c = A351114.
%t A386574 Table[Sum[(1 - Ceiling[DivisorSigma[1, d]/EulerPhi[d]] + Floor[DivisorSigma[1, d]/EulerPhi[d]]) MoebiusMu[d]^2, {d, Divisors[n]}], {n, 100}]
%Y A386574 Cf. A005117 (squarefree numbers), A020492 (balanced numbers), A351114, A386573.
%K A386574 nonn
%O A386574 1,2
%A A386574 _Wesley Ivan Hurt_, Jul 26 2025