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 A334196 #14 Aug 18 2024 16:04:38 %S A334196 0,1,1,0,1,-1,1,0,0,0,1,-1,1,-1,1,0,1,-2,1,0,0,0,1,-1,1,-1,0,0,1,-1,1, %T A334196 0,0,0,0,-1,1,-1,1,0,1,-2,1,0,0,0,1,-1,0,0,1,-1,1,-2,2,-1,0,0,1,-1,1, %U A334196 -1,0,1,0,-1,1,0,0,-1,1,-1,1,-1,1,-1,1,-1,1,0,-1,1,1,-2,2,-2,1,0,1,-2,1,0,0,0,0,0,1,-2,1,0,1,-1,1,-1,0 %N A334196 a(1) = 0, then after the first differences of A003434. %C A334196 Also, from a(2) onward the first differences of A049108, and from a(3) onward the first differences of A032358. %H A334196 Antti Karttunen, <a href="/A334196/b334196.txt">Table of n, a(n) for n = 1..65537</a> %F A334196 a(1) = 0; and for n > 1, a(n) = A003434(n) - A003434(n-1). %t A334196 Differences[Array[Length[FixedPointList[EulerPhi, #]] &, 100, 0]] (* _Paolo Xausa_, Aug 18 2024 *) %o A334196 (PARI) %o A334196 A003434(n) = for(k=0, n, n>1 || return(k); n=eulerphi(n)); %o A334196 A334196(n) = if(1==n,0,A003434(n)-A003434(n-1)); %Y A334196 Cf. A000010, A003434, A032358, A049108, A334195. %K A334196 sign %O A334196 1,18 %A A334196 _Antti Karttunen_, Apr 18 2020