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 A175253 #11 Mar 22 2024 06:48:40
%S A175253 0,1,0,0,1,0,0,0,1,1,1,0,0,0,0,1,1,0,1,0,1,1,1,0,1,1,1,0,1,0,0,0,1,1,
%T A175253 1,0,1,0,0,0,1,0,1,0,1,1,1,0,1,1,1,1,1,0,1,0,0,1,1,0,1,0,0,1,1,1,1,0,
%U A175253 1,1,1,0,1,0,1,1,1,0,1,0,1,1,1,0,1
%N A175253 a(n) = characteristic function of numbers k such that A000203(m) = k has no solution for any m, where A000203(m) = sum of divisors of m.
%C A175253 a(n) = characteristic function of numbers from A007369(n). a(n) = 1 if A000203(m) not equal to n for any m, else 0. a(n) = 1 for such n that A054973(n) = 0. a(n) = 0 for such n that A054973(n) >= 1. a(n) + A175192(n) = A000012(n).
%H A175253 Jaroslav Krizek, <a href="/A175253/b175253.txt">Table of n, a(n) for n = 1..10000</a>
%t A175253 seq[max_] := Module[{t = Table[0, {max}]}, t[[Complement[Range[max], Table[ DivisorSigma[1, n], {n, 1, max}]]]] = 1; t]; seq[100] (* _Amiram Eldar_, Mar 22 2024 *)
%Y A175253 Cf. A074753, A202275, A202276, A175523, A007369, A007368, A007609.
%K A175253 nonn
%O A175253 1,1
%A A175253 _Jaroslav Krizek_, Mar 14 2010
%E A175253 More terms from _Jaroslav Krizek_, Dec 25 2011.