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A266594
Total number of ON (black) cells after n iterations of the "Rule 37" elementary cellular automaton starting with a single ON (black) cell.
1
1, 2, 5, 7, 10, 16, 19, 29, 32, 46, 49, 67, 70, 92, 95, 121, 124, 154, 157, 191, 194, 232, 235, 277, 280, 326, 329, 379, 382, 436, 439, 497, 500, 562, 565, 631, 634, 704, 707, 781, 784, 862, 865, 947, 950, 1036, 1039, 1129, 1132, 1226, 1229, 1327, 1330, 1432
OFFSET
0,2
REFERENCES
S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.
FORMULA
Conjectures from Colin Barker, Jan 02 2016 and Apr 18 2019: (Start)
a(n) = (n^2-(-1)^n*(n-3)+5)/2 for n>0.
a(n) = a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5) for n>5.
G.f.: (1+x+x^2-2*x^4+3*x^5) / ((1-x)^3*(1+x)^2).
(End)
MATHEMATICA
rule=37; rows=20; ca=CellularAutomaton[rule, {{1}, 0}, rows-1, {All, All}]; (* Start with single black cell *) catri=Table[Take[ca[[k]], {rows-k+1, rows+k-1}], {k, 1, rows}]; (* Truncated list of each row *) nbc=Table[Total[catri[[k]]], {k, 1, rows}]; (* Number of Black cells in stage n *) Table[Total[Take[nbc, k]], {k, 1, rows}] (* Number of Black cells through stage n *)
CROSSREFS
Cf. A266588.
Sequence in context: A159942 A102339 A172410 * A103871 A068817 A156779
KEYWORD
nonn,easy
AUTHOR
Robert Price, Jan 01 2016
STATUS
approved