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 A266073 Number of OFF (white) cells in the n-th iteration of the "Rule 3" elementary cellular automaton starting with a single ON (black) cell. 2
 0, 2, 4, 2, 8, 2, 12, 2, 16, 2, 20, 2, 24, 2, 28, 2, 32, 2, 36, 2, 40, 2, 44, 2, 48, 2, 52, 2, 56, 2, 60, 2, 64, 2, 68, 2, 72, 2, 76, 2, 80, 2, 84, 2, 88, 2, 92, 2, 96, 2, 100, 2, 104, 2, 108, 2, 112, 2, 116, 2, 120, 2, 124, 2, 128, 2, 132, 2, 136, 2, 140, 2 (list; graph; refs; listen; history; text; internal format)
 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..999 Eric Weisstein's World of Mathematics, Elementary Cellular Automaton FORMULA Empirical g.f.: (-2*(-x - 2*x^2 + x^3))/(-1 + x^2)^2. - Michael De Vlieger, Dec 21 2015 Conjectures from Colin Barker, Dec 21 2015 and Apr 17 2019: (Start) a(n) = (-1)^n*n+n-(-1)^n+1. a(n) = 2*a(n-2) - a(n-4) for n>3. (End) EXAMPLE From Michael De Vlieger, Dec 21 2015: (Start) First 12 rows, replacing "0" with "." for better visibility of OFF cells, followed by the total number of 0's per row:                       .                        =  0                     . 0 0                      =  2                   0 0 0 . 0                    =  4                 . . . . 0 0 .                  =  2               0 0 0 0 0 0 . 0 0                =  8             . . . . . . . 0 0 . .              =  2           0 0 0 0 0 0 0 0 0 . 0 0 0            = 12         . . . . . . . . . . 0 0 . . .          =  2       0 0 0 0 0 0 0 0 0 0 0 0 . 0 0 0 0        = 16     . . . . . . . . . . . . . 0 0 . . . .      =  2   0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 . 0 0 0 0 0    = 20 . . . . . . . . . . . . . . . . 0 0 . . . . .  =  2 (End) CROSSREFS Sequence in context: A209675 A307669 A171977 * A059866 A278262 A093895 Adjacent sequences:  A266070 A266071 A266072 * A266074 A266075 A266076 KEYWORD nonn,easy AUTHOR Robert Price, Dec 20 2015 STATUS approved

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Last modified April 10 19:06 EDT 2021. Contains 342853 sequences. (Running on oeis4.)