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 A287132 Decimal representation of the diagonal from the origin to the corner of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 245", based on the 5-celled von Neumann neighborhood. 4
 1, 1, 0, 7, 24, 31, 96, 63, 384, 255, 1536, 1023, 6144, 4095, 24576, 16383, 98304, 65535, 393216, 262143, 1572864, 1048575, 6291456, 4194303, 25165824, 16777215, 100663296, 67108863, 402653184, 268435455, 1610612736, 1073741823, 6442450944, 4294967295 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS Initialized with a single black (ON) cell at stage zero. REFERENCES S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 170. LINKS Robert Price, Table of n, a(n) for n = 0..126 Robert Price, Diagrams of first 20 stages N. J. A. Sloane, On the Number of ON Cells in Cellular Automata, arXiv:1503.01168 [math.CO], 2015 Eric Weisstein's World of Mathematics, Elementary Cellular Automaton S. Wolfram, A New Kind of Science Wolfram Research, Wolfram Atlas of Simple Programs FORMULA Conjectures from Colin Barker, May 20 2017: (Start) G.f.: (1 + x - 5*x^2 + 2*x^3 + 28*x^4 - 24*x^6 - 64*x^7 + 64*x^9) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 + 2*x)). a(n) = 3*2^(n-1) for n>5 and even. a(n) = 2^(n-1) - 1 for n>5 and odd. (End) MATHEMATICA CAStep[rule_, a_] := Map[rule[[10 - #]] &, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}]; code = 245; stages = 128; rule = IntegerDigits[code, 2, 10]; g = 2 * stages + 1; (* Maximum size of grid *) a = PadLeft[{{1}}, {g, g}, 0, Floor[{g, g}/2]]; (* Initial ON cell on grid *) ca = a; ca = Table[ca = CAStep[rule, ca], {n, 1, stages + 1}]; PrependTo[ca, a]; (* Trim full grid to reflect growth by one cell at each stage *) k = (Length[ca[[1]]] + 1)/2; ca = Table[Table[Part[ca[[n]] [[j]], Range[k + 1 - n, k - 1 + n]], {j, k + 1 - n, k - 1 + n}], {n, 1, k}]; Table[FromDigits[Part[ca[[i]] [[i]], Range[i, 2 * i - 1]], 10], {i, 1, stages - 1}] CROSSREFS Cf. A287129, A287130, A287131. Sequence in context: A070410 A077035 A076602 * A287193 A076673 A270422 Adjacent sequences:  A287129 A287130 A287131 * A287133 A287134 A287135 KEYWORD nonn,easy AUTHOR Robert Price, May 20 2017 STATUS approved

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Last modified January 28 18:02 EST 2022. Contains 350657 sequences. (Running on oeis4.)