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.

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

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