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 A130638 #15 Oct 04 2017 14:03:13
%S A130638 0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,1,
%T A130638 0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,
%U A130638 0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1,0,0,0,1,0,0,0,0,0,1,0
%N A130638 a(n) = 1 iff d(n) = d(n+1), otherwise a(n)=0, where d(n) is the number of divisors of n, A000005.
%H A130638 Antti Karttunen, <a href="/A130638/b130638.txt">Table of n, a(n) for n = 1..10000</a>
%H A130638 <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%t A130638 Table[If[Length[Divisors[n]] == Length[Divisors[n + 1]], 1, 0], {n, 1, 80}] (* _Stefan Steinerberger_, Aug 12 2007 *)
%o A130638 (PARI) A130638(n) = (numdiv(n)==numdiv(n+1)); \\ _Antti Karttunen_, Oct 04 2017
%Y A130638 Characteristic function of A005237.
%Y A130638 Cf. A000005.
%K A130638 nonn
%O A130638 1,1
%A A130638 _Giovanni Teofilatto_, Aug 11 2007
%E A130638 Corrected and extended by _Stefan Steinerberger_, Aug 12 2007
%E A130638 More terms (up to a(105)) from _Antti Karttunen_, Oct 04 2017