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 A232031 Number of (n+1) X (1+1) 0..1 arrays with every element equal to some horizontal, vertical or antidiagonal neighbor, with top left element zero. 4
 3, 11, 37, 129, 450, 1568, 5464, 19041, 66354, 231230, 805789, 2808009, 9785334, 34099877, 118831060, 414101811, 1443059667, 5028766229, 17524216333, 61068290730, 212810436816, 741600615908, 2584325664397, 9005843571858 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 1 of A232038. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 4*a(n-1) - 2*a(n-2) + a(n-3) - a(n-4). Empirical g.f.: x*(3 - x - x^2) / (1 - 4*x + 2*x^2 - x^3 + x^4). - Colin Barker, Mar 19 2018 EXAMPLE Some solutions for n=7: ..0..0....0..0....0..0....0..1....0..0....0..0....0..0....0..0....0..1....0..0 ..0..0....0..0....0..1....0..1....1..1....1..1....0..1....0..0....0..1....0..0 ..0..0....1..1....1..0....0..0....1..0....1..0....0..1....0..1....1..1....0..0 ..0..0....0..0....0..1....0..0....0..1....1..0....1..0....0..1....1..0....1..1 ..1..1....1..1....1..1....1..1....1..0....0..1....1..0....1..1....0..0....1..0 ..1..0....0..0....1..1....0..1....1..0....1..1....0..0....1..0....1..0....1..0 ..0..0....1..1....1..0....0..0....1..1....0..0....0..1....0..1....1..1....0..0 ..1..1....0..0....1..0....0..0....0..0....1..1....0..1....0..1....0..0....0..0 CROSSREFS Cf. A232038. Sequence in context: A046722 A214996 A180168 * A047102 A109000 A183511 Adjacent sequences: A232028 A232029 A232030 * A232032 A232033 A232034 KEYWORD nonn AUTHOR R. H. Hardin, Nov 17 2013 STATUS approved

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Last modified September 27 05:08 EDT 2023. Contains 365674 sequences. (Running on oeis4.)