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 A278520 #8 Dec 12 2016 09:11:57 %S A278520 0,0,0,0,0,1,0,0,-1,2,0,2,0,3,0,0,0,0,0,4,1,4,0,3,-2,5,-2,6,0,2,0,0,2, %T A278520 6,-1,1,0,7,3,6,0,4,0,8,0,8,0,4,-3,0,4,10,0,-1,0,9,5,9,0,4,0,10,2,0,1, %U A278520 6,0,12,6,2,0,2,0,11,-2,14,-2,8,0,8,-3,12,0,7,2,13,7,12,0,2,-1,16,8,14,3,5,0,0,4,2,0,10,0,15,0,15,0,0,0,4,9,12,0,12 %N A278520 a(n) = A243503(n) - A056239(n). %C A278520 The 223rd zero in this sequence occurs at n=1078 (a(1078) = 0, 1078 = 2*7*7*11) and it is the first zero that is not included in A241912. %H A278520 Antti Karttunen, <a href="/A278520/b278520.txt">Table of n, a(n) for n = 1..8192</a> %F A278520 a(n) = A243503(n) - A056239(n). %F A278520 a(A241912(n)) = 0 [but obtains zeros also for other values, see comments.] %Y A278520 Cf. A056239, A243503. %Y A278520 Cf. A241912 (gives the subset of the indices of zeros). %K A278520 sign %O A278520 1,10 %A A278520 _Antti Karttunen_, Dec 11 2016