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 A174898 #12 Oct 20 2017 14:26:57 %S A174898 0,0,0,1,0,1,0,0,1,1,0,1,0,1,1,1,0,1,0,1,1,1,0,1,1,1,0,1,0,1,0,1,1,1, %T A174898 1,0,0,1,1,1,0,1,0,1,1,1,0,1,1,1,1,1,0,1,1,1,1,1,0,1,0,1,1,0,1,1,0,1, %U A174898 1,1,0,1,0,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,0,0,1,0,1,1 %N A174898 a(n) = characteristic function of numbers k such that A007955(m) = k has no solution for any m, where A007955(m) = product of divisors of m. %C A174898 a(n) = characteristic function of numbers from A174896(n). %C A174898 a(n) = 1 if A007955(m) not equal to n for any m, else 0. %H A174898 Antti Karttunen, <a href="/A174898/b174898.txt">Table of n, a(n) for n = 1..20000</a> (computed from the b-file of A174897) %H A174898 <a href="/index/Ch#char_fns">Index entries for characteristic functions</a> %F A174898 a(n) = 1 - A174897(n). %Y A174898 Cf. A007955, A174896, A174897. %K A174898 nonn %O A174898 1,1 %A A174898 _Jaroslav Krizek_, Apr 01 2010 %E A174898 More terms from _Antti Karttunen_, Oct 20 2017