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 A253742 Number of (n+1) X (1+1) 0..2 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically. 1
 81, 450, 1998, 7803, 28107, 95940, 315576, 1011357, 3181653, 9876870, 30368034, 92726271, 281717919, 852821640, 2574980172, 7760330145, 23356488105, 70229896650, 211029428790, 633805512579, 1902926487411, 5711950356300 (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) = 9*a(n-1) - 31*a(n-2) + 51*a(n-3) - 40*a(n-4) + 12*a(n-5). Empirical g.f.: 9*x*(9 - 31*x + 51*x^2 - 40*x^3 + 12*x^4) / ((1 - x)^2*(1 - 2*x)^2*(1 - 3*x)). - Colin Barker, Dec 17 2018 EXAMPLE Some solutions for n=4: ..2..0....0..1....1..0....0..2....0..1....0..1....1..1....2..0....0..1....1..2 ..1..0....0..2....1..0....1..0....0..0....0..1....0..0....2..1....0..0....2..1 ..2..1....0..2....1..0....2..1....1..1....1..1....2..1....2..1....2..2....1..0 ..2..1....2..2....2..1....0..0....1..1....2..1....2..1....2..2....2..0....2..1 ..2..1....1..1....2..0....1..2....2..2....0..1....2..1....0..2....2..2....1..1 CROSSREFS Column 1 of A253749. Sequence in context: A204230 A235441 A235406 * A204223 A205215 A206223 Adjacent sequences:  A253739 A253740 A253741 * A253743 A253744 A253745 KEYWORD nonn AUTHOR R. H. Hardin, Jan 11 2015 STATUS approved

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Last modified June 24 21:50 EDT 2021. Contains 345433 sequences. (Running on oeis4.)