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 A279253 Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 155", based on the 5-celled von Neumann neighborhood. 4
 1, 2, 5, 14, 5, 46, 85, 190, 325, 942, 277, 2750, 5445, 11182, 21781, 43710, 86085, 175790, 332821, 699326, 1377605, 2812846, 5588245, 11184830, 22368325, 44740270, 89461781, 178957246, 357844293, 715828142, 1431307541, 2863655614, 5726294085, 11453509294 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 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 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 Robert Price, Diagrams of first 20 stages MATHEMATICA CAStep[rule_, a_] := Map[rule[[10 - #]] &, ListConvolve[{{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}, a, 2], {2}]; code = 155; 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]], 2], {i , 1, stages - 1}] CROSSREFS Cf. A279250, A279251, A279252. Sequence in context: A279876 A329494 A016737 * A279958 A324982 A289682 Adjacent sequences:  A279250 A279251 A279252 * A279254 A279255 A279256 KEYWORD nonn,easy AUTHOR Robert Price, Dec 08 2016 STATUS approved

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Last modified June 24 02:11 EDT 2021. Contains 345408 sequences. (Running on oeis4.)