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 A281208 Number of 4 X n 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
 0, 38, 168, 270, 470, 804, 1358, 2284, 3834, 6432, 10786, 18080, 30290, 50712, 84838, 141812, 236846, 395228, 658966, 1097796, 1827410, 3039624, 5052282, 8391768, 13929370, 23106544, 38306878, 63470044, 105104774, 173959572, 287777246 (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) - 2*a(n-3) + 4*a(n-4) - a(n-6) for n>10. Empirical g.f.: 2*x^2*(19 + 8*x - 125*x^2 + 69*x^3 + 94*x^4 - 55*x^5 - 17*x^6 + 13*x^7 + x^8) / ((1 - x)^2*(1 - x - x^2)^2). - Colin Barker, Feb 18 2019 EXAMPLE Some solutions for n=4: ..0..0..0..1. .0..0..0..1. .0..0..1..0. .0..1..1..0. .0..0..1..0 ..0..1..0..0. .1..1..0..0. .1..0..1..1. .0..0..1..1. .0..1..0..1 ..0..1..1..0. .0..1..1..0. .1..0..0..1. .1..0..0..1. .0..1..0..1 ..0..0..1..1. .0..0..1..0. .1..0..1..0. .1..0..1..0. .0..1..0..1 CROSSREFS Row 4 of A281205. Sequence in context: A224739 A135176 A318625 * A100167 A100168 A137022 Adjacent sequences: A281205 A281206 A281207 * A281209 A281210 A281211 KEYWORD nonn AUTHOR R. H. Hardin, Jan 17 2017 STATUS approved

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Last modified August 11 23:41 EDT 2024. Contains 375082 sequences. (Running on oeis4.)