A098725 - OEIS

%I #11 Apr 04 2024 10:04:39

%S 0,1,1,1,0,1,1,1,0,1,1,1,0,1,0,1,0,1,1,1,0,1,1,1,0,1,1,1,0,1,0,1,0,1,

%T 1,1,0,1,1,1,0,1,1,1,0,1,0,1,0,1,1,1,0,1,0,1,0,1,1,1,0,1,0,1,0,1,1,1,

%U 0,1,1,1,0,1,1,1,0,1,0,1,0,1,1,1,0,1,1,1,0,1,1,1,0,1,0,1,0,1,1,1,0,1

%N a(4n) = 0, a(2n+1) = 1, a(4n+2) = a(n+1).

%C Apparently, the first differences of A072894.

%H Antti Karttunen, <a href="/A098725/b098725.txt">Table of n, a(n) for n = 0..65537</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%t A098725[n_] := Which[OddQ[n], 1, Divisible[n, 4], 0, True, A098725[(n+2)/4]];

%t Array[A098725, 100, 0] (* _Paolo Xausa_, Apr 04 2024 *)

%o (PARI) a(n)=if(n%2==1,1,if(n%4==0,0,a((n-2)/4+1)))

%K nonn

%O 0,1

%A _Ralf Stephan_, Oct 15 2004