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 A161913 #9 Feb 03 2019 14:56:16 %S A161913 4,9,10,11,12,15,16,19,20,21,23,25,26,28,29,30,31,33,34,35,36,37,39, %T A161913 40,42,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64, %U A161913 66,67,68,69,70,71,72,73,74,75,77,78 %N A161913 Numbers k such that A001223(k) <> A000005(k). %H A161913 Nathaniel Johnston, <a href="/A161913/b161913.txt">Table of n, a(n) for n = 1..10000</a> %H A161913 Omar E. Pol, <a href="http://www.polprimos.com/imagenespub/polprdipi.jpg">Illustration: Divisors and pi(x)</a> %p A161913 p2:=2:for n from 1 to 78 do p1:=p2:p2:=ithprime(n+1):if(p2-p1<>tau(n))then print(n);fi:od: # _Nathaniel Johnston_, Apr 15 2011 %Y A161913 Cf. A000005, A001223, A068526, A161911, A161912, A162188, A162189. %K A161913 easy,nonn %O A161913 1,1 %A A161913 _Omar E. Pol_, Jul 04 2009