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 A237629 Number of (n+1) X (n+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
 81, 636, 1310, 2012, 4622, 9368, 18344, 44292, 102536, 211268, 402152, 1015572, 2337608, 4914788, 9150632, 23921652, 54827528, 116999108, 214315112, 574558932, 1312885448, 2831048228, 5126666792, 13988255412, 31897292168, 69273334148 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..36 FORMULA Empirical: a(n) = 4*a(n-2) + 25*a(n-4) - 100*a(n-6) for n>11. Empirical g.f.: x*(81 + 636*x + 986*x^2 - 532*x^3 - 2643*x^4 - 14580*x^5 - 24794*x^6 + 20120*x^7 + 44610*x^8 + 1100*x^9 - 4392*x^10) / ((1 - 2*x)*(1 + 2*x)*(1 - 5*x^2)*(1 + 5*x^2)). - Colin Barker, Oct 23 2018 EXAMPLE Some solutions for n=5: ..1..0..0..1..2..1....1..0..2..1..0..1....2..1..0..1..2..2....1..0..1..2..0..1 ..1..0..1..2..0..0....1..2..0..0..0..2....0..2..0..0..0..2....2..0..0..0..2..1 ..0..0..2..1..0..1....2..1..0..1..2..1....0..1..2..1..0..1....1..2..1..0..1..2 ..1..2..0..0..0..2....0..0..0..2..1..0....0..0..0..2..0..0....0..0..2..0..0..0 ..2..1..0..1..2..0....0..1..2..0..0..0....2..1..0..1..2..1....1..0..1..2..1..0 ..0..0..0..2..1..0....1..2..1..0..2..1....2..1..0..0..0..2....2..0..0..0..2..1 CROSSREFS Diagonal of A237637. Sequence in context: A322240 A185856 A185848 * A236720 A187441 A187433 Adjacent sequences:  A237626 A237627 A237628 * A237630 A237631 A237632 KEYWORD nonn AUTHOR R. H. Hardin, Feb 10 2014 STATUS approved

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Last modified May 16 08:07 EDT 2021. Contains 343940 sequences. (Running on oeis4.)