OFFSET
0,2
REFERENCES
S. Wolfram, A New Kind of Science, Wolfram Media, 2002; p. 55.
LINKS
Robert Price, Table of n, a(n) for n = 0..1000
Eric Weisstein's World of Mathematics, Elementary Cellular Automaton
S. Wolfram, A New Kind of Science
FORMULA
From Colin Barker, Jan 17 2016 and Apr 17 2019: (Start)
a(n) = 11*a(n-1)-11*a(n-2)+11*a(n-3)-10*a(n-4) for n>3.
G.f.: (1-x+x^2) / ((1-x)*(1-10*x)*(1+x^2)).
(End)
a(n) = floor(100100*10^n/99990). - Karl V. Keller, Jr., Aug 21 2021
MATHEMATICA
rule=147; 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 *) mc=Table[catri[[k]][[k]], {k, 1, rows}]; (* Keep only middle cell from each row *) Table[FromDigits[Take[mc, k]], {k, 1, rows}] (* Binary Representation of Middle Column *)
PROG
(Python) print([100100*10**n//99990 for n in range(50)]) # Karl V. Keller, Jr., Aug 21 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Robert Price, Jan 17 2016
STATUS
approved