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A253079 a(n) = if n is even, number of ON cells at stage n of two-dimensional 5-neighbor outer totalistic cellular automaton defined by "Rule 489" or if n is odd, number of OFF cells. 2
1, 5, 13, 17, 33, 21, 65, 65, 97, 61, 145, 153, 177, 149, 257, 249, 345, 237, 433, 409, 465, 389, 601, 521, 745, 501, 897, 713, 897, 709, 1081, 921, 1281, 877, 1481, 1121, 1505, 1125, 1817, 1393, 1993, 1309, 2209, 1577, 2401, 1653, 2497, 1953, 2985, 1901 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

If we subtract 1 and divide by 4, the result (A253080) almost looks like it should have a simple recurrence. It would be nice to know more.

REFERENCES

S. Wolfram, A New Kind of Science, Wolfram Media, 2002; pp. 173-175.

LINKS

Table of n, a(n) for n=0..49.

N. J. A. Sloane, Illustration of generations 0-23

Index entries for sequences related to cellular automata

MATHEMATICA

Map[Function[Apply[Plus, Flatten[ #1]]], CellularAutomaton[{ 489, {2, {{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}}, {1, 1}}, {{{1}}, 0}, 200]] (* then subtract the odd-indexed terms from 201^2 (a constant which depends on Mathematica's choice of grid size) *)

ArrayPlot /@ CellularAutomaton[{489, {2, {{0, 2, 0}, {2, 1, 2}, {0, 2, 0}}}, {1, 1}}, {{{1}}, 0}, 23]

CROSSREFS

Cf. A253080, A169699, A246316, A246318, A246325, A246326, ...

Sequence in context: A273950 A268511 A038938 * A184851 A211425 A245906

Adjacent sequences:  A253076 A253077 A253078 * A253080 A253081 A253082

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 04 2015

STATUS

approved

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Last modified September 23 16:01 EDT 2020. Contains 337310 sequences. (Running on oeis4.)