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 A334195 #9 Apr 18 2020 19:45:41 %S A334195 0,1,0,1,0,0,0,1,-1,1,0,0,0,0,0,1,0,-1,0,1,-1,1,0,0,0,0,-1,1,0,0,0,1, %T A334195 -1,1,-1,0,0,0,0,1,0,-1,0,1,-1,1,0,0,-1,1,0,0,0,-1,1,0,-1,1,0,0,0,0, %U A334195 -1,2,-1,0,0,1,-1,0,0,0,0,0,0,0,0,0,0,1,-2,2,0,-1,1,-1,0,1,0,-1,0,1,-1,1,-1,1,0,-1,0,1,0,0,0,0,-1 %N A334195 a(1) = 0, then after the first differences of A064415. %H A334195 Antti Karttunen, <a href="/A334195/b334195.txt">Table of n, a(n) for n = 1..65537</a> %F A334195 a(1) = 0; and for n > 1, a(n) = A064415(n) - A064415(n-1). %F A334195 a(n) = A334090(n) - A334091(n). %o A334195 (PARI) %o A334195 A003434(n) = for(k=0, n, n>1 || return(k); n=eulerphi(n)); %o A334195 A064415(n) = if(1==n,0, A003434(n)-(n%2)); %o A334195 A334195(n) = if(1==n,0,A064415(n)-A064415(n-1)); %Y A334195 Cf. A003434, A064415, A334090, A334091, A334196. %Y A334195 Also, from a(3) onward the first differences of A054725. %K A334195 sign %O A334195 1,64 %A A334195 _Antti Karttunen_, Apr 18 2020