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 A237227 Number of (n+1) X (1+1) 0..2 arrays with the maximum plus the minimum of every 2 X 2 subblock differing from its horizontal and vertical neighbors by exactly one. 1
 81, 268, 928, 2784, 9628, 28912, 100008, 300256, 1038560, 3118208, 10785696, 32383104, 112011072, 336303872, 1163253760, 3492571136, 12080581376, 36270926848, 125458829824, 376679553024, 1302910621696, 3911879237632 (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) = 8*a(n-2) + 24*a(n-4) + 8*a(n-6) for n>7. Empirical g.f.: x*(81 + 268*x + 280*x^2 + 640*x^3 + 260*x^4 + 208*x^5 + 64*x^6) / ((1 + 2*x^2)*(1 - 10*x^2 - 4*x^4)). - Colin Barker, Oct 21 2018 EXAMPLE Some solutions for n=5: ..2..1....1..2....0..2....1..0....0..2....2..1....2..0....1..0....2..1....2..1 ..0..0....0..0....1..0....2..1....0..0....2..2....0..1....1..0....1..0....0..0 ..1..0....1..0....0..1....1..1....1..0....0..1....0..0....2..1....1..1....1..0 ..2..2....2..2....2..2....1..1....1..2....0..1....2..2....1..2....1..1....2..2 ..1..1....1..2....1..1....2..2....1..1....1..2....1..2....0..1....0..0....1..2 ..0..2....1..0....1..1....0..0....0..2....2..1....2..0....0..1....0..2....0..0 CROSSREFS Column 1 of A237234. Sequence in context: A236746 A236739 A237234 * A206094 A202333 A207042 Adjacent sequences:  A237224 A237225 A237226 * A237228 A237229 A237230 KEYWORD nonn AUTHOR R. H. Hardin, Feb 05 2014 STATUS approved

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Last modified December 2 08:31 EST 2021. Contains 349437 sequences. (Running on oeis4.)