A327985 - OEIS

%I #11 Jun 29 2023 02:30:20

%S 2,6,7,10,11,12,14,17,18,20,21,25,27,31,32,36,38,40,43,44,45,46,49,50,

%T 52,54,57,59,61,68,69,70,71,76,77,78,80,82,86,87,88,89,90,92,93,95,98,

%U 99,100,104,105,106,109,112,115,117,118,119,120,121,122,123,125,126,127,133,137,139,140,144,145,146,150,152,156

%N Positions of zeros in A051023, the middle column of rule-30 1-D cellular automaton, when started from a lone 1 cell.

%H Antti Karttunen, <a href="/A327985/b327985.txt">Table of n, a(n) for n = 1..100000</a>

%H <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>

%t A327985list[upto_]:=Flatten[Position[CellularAutomaton[30,{{1},0},{upto,{{0}}}],0]]-1;A327985list[200] (* _Paolo Xausa_, Jun 28 2023 *)

%o (PARI)

%o A269160(n) = bitxor(n, bitor(2*n, 4*n)); \\ From A269160.

%o A110240(n) = if(!n,1,A269160(A110240(n-1)));

%o A051023(n) = ((A110240(n)>>n)%2);

%o isA327985(n) = !A051023(n);

%o (PARI) A327985write(up_to) = { my(s=1, n=0, k=0); while(k<up_to, if(!((s>>n)%2), k++; write("b327985.txt", k, " ", n)); s = A269160(s); n++); (n); }; \\ For fast creation of b-files.

%Y Cf. A051023, A226474 (characteristic function), A110240, A269160.

%Y Cf. A327980 (first differences), A327984 (complement).

%K nonn

%O 1,1

%A _Antti Karttunen_, Oct 03 2019