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A266610
Decimal representation of the n-th iteration of the "Rule 41" elementary cellular automaton starting with a single ON (black) cell.
2
1, 0, 5, 100, 1, 2040, 5, 32740, 1, 524280, 5, 8388580, 1, 134217720, 5, 2147483620, 1, 34359738360, 5, 549755813860, 1, 8796093022200, 5, 140737488355300, 1, 2251799813685240, 5, 36028797018963940, 1, 576460752303423480, 5, 9223372036854775780, 1
OFFSET
0,3
FORMULA
Conjectures from Colin Barker, Jan 02 2016 and Apr 18 2019: (Start)
a(n) = 16*a(n-2)+a(n-4)-16*a(n-6) for n>5.
G.f.: (1-11*x^2+100*x^3-80*x^4+440*x^5) / ((1-x)*(1+x)*(1-4*x)*(1+4*x)*(1+x^2)).
(End)
Conjecture: a(n) = 2*4^n + 2 - 10*(n mod 4) for odd n; a(n) = 5^((n mod 4)/2) for even n. - Karl V. Keller, Jr., Oct 07 2021
MATHEMATICA
rule=41; 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 *) Table[FromDigits[catri[[k]], 2], {k, 1, rows}] (* Decimal Representation of Rows *)
CROSSREFS
Sequence in context: A277418 A318061 A147539 * A156276 A322715 A208348
KEYWORD
nonn,easy
AUTHOR
Robert Price, Jan 01 2016
STATUS
approved