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 A281200 Number of n X 3 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards. 1
 1, 14, 56, 168, 448, 1120, 2688, 6272, 14336, 32256, 71680, 157696, 344064, 745472, 1605632, 3440640, 7340032, 15597568, 33030144, 69730304, 146800640, 308281344, 645922816, 1350565888, 2818572288, 5872025600, 12213813248, 25367150592 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 4*a(n-1) - 4*a(n-2) for n>3. Conjectures from Colin Barker, Feb 16 2019: (Start) G.f.: x*(1 + 10*x + 4*x^2) / (1 - 2*x)^2. a(n) = 7*2^(n-1) * (n-1) for n>1. (End) EXAMPLE Some solutions for n=4: ..0..1..0. .0..1..1. .0..0..1. .0..1..0. .0..0..1. .0..0..0. .0..1..1 ..1..1..0. .0..1..0. .1..0..1. .0..1..1. .1..1..0. .1..1..0. .1..0..1 ..0..1..0. .0..1..0. .1..0..1. .1..0..1. .0..1..0. .0..1..0. .1..0..1 ..0..1..0. .0..1..0. .1..1..0. .1..0..0. .0..1..0. .0..1..1. .0..1..0 CROSSREFS Column 3 of A281205. Sequence in context: A192846 A212347 A115129 * A212341 A067326 A202242 Adjacent sequences: A281197 A281198 A281199 * A281201 A281202 A281203 KEYWORD nonn AUTHOR R. H. Hardin, Jan 17 2017 STATUS approved

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Last modified February 29 23:21 EST 2024. Contains 370428 sequences. (Running on oeis4.)