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 A237631 Number of (n+1) X (2+1) 0..2 arrays with the upper median of every 2 X 2 subblock differing from its horizontal and vertical neighbors by exactly one. 1
 260, 636, 1220, 2356, 4500, 8594, 16448, 31672, 60362, 116180, 223768, 429680, 822032, 1584164, 3047968, 5848520, 11216480, 21603248, 41526472, 79692176, 153032384, 294531296, 565871200, 1086330032, 2087379872, 4014989408 (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) = 3*a(n-3) + 10*a(n-4) - 12*a(n-7) - 6*a(n-8) for n>12. Empirical g.f.: 2*x*(130 + 318*x + 610*x^2 + 788*x^3 - 4*x^4 - 713*x^5 - 1410*x^6 - 1134*x^7 - 614*x^8 - 324*x^9 - 68*x^10 + 5*x^11) / (1 - 3*x^3 - 10*x^4 + 12*x^7 + 6*x^8). - Colin Barker, Oct 24 2018 EXAMPLE Some solutions for n=5: ..2..1..1....1..1..2....0..1..0....2..0..1....2..2..1....0..1..1....0..1..2 ..0..2..1....0..2..1....2..0..0....2..1..0....1..0..0....0..0..2....1..2..1 ..0..1..2....2..1..0....2..1..2....0..0..0....2..1..0....1..2..1....2..0..0 ..0..0..0....0..0..0....0..0..2....0..1..2....1..2..0....2..1..0....1..0..1 ..2..1..0....0..1..2....1..0..1....1..2..1....0..1..2....0..0..0....0..0..2 ..2..0..2....0..2..1....1..2..2....2..1..1....0..0..0....0..1..2....1..2..0 CROSSREFS Column 2 of A237637. Sequence in context: A253504 A154379 A185793 * A202585 A037219 A290040 Adjacent sequences:  A237628 A237629 A237630 * A237632 A237633 A237634 KEYWORD nonn AUTHOR R. H. Hardin, Feb 10 2014 STATUS approved

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Last modified January 26 05:13 EST 2022. Contains 350572 sequences. (Running on oeis4.)