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 A206981 Number of n X 2 0..1 arrays avoiding the patterns 0 1 0 or 1 0 1 in any row, column, diagonal or antidiagonal. 32
 4, 16, 36, 100, 256, 676, 1764, 4624, 12100, 31684, 82944, 217156, 568516, 1488400, 3896676, 10201636, 26708224, 69923044, 183060900, 479259664, 1254718084, 3284894596, 8599965696, 22515002500, 58945041796, 154320122896, 404015326884 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 2*a(n-1) + 2*a(n-2) - a(n-3). G.f.: -4*x*(-1-2*x+x^2) / ( (1+x)*(x^2-3*x+1) ). Empirical: a(n) = (A080097(n)+1)*4. - Martin Ettl, Nov 13 2012 EXAMPLE Some solutions for n=4 ..1..1....0..0....0..0....0..0....1..1....0..1....1..1....0..1....1..0....0..0 ..0..1....0..1....1..0....1..0....1..1....1..1....1..1....1..0....0..1....1..1 ..0..0....1..1....1..1....1..0....1..1....1..0....1..1....1..0....0..1....1..1 ..1..0....1..1....0..1....1..0....1..1....1..0....0..0....1..0....1..0....0..0 CROSSREFS Column 2 of A206987. Cf. A080097. Sequence in context: A005722 A372635 A075408 * A318149 A233409 A181795 Adjacent sequences: A206978 A206979 A206980 * A206982 A206983 A206984 KEYWORD nonn AUTHOR R. H. Hardin, Feb 14 2012 STATUS approved

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Last modified May 26 23:01 EDT 2024. Contains 372847 sequences. (Running on oeis4.)