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 A253441 Number of (7+1) X (n+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally. 1
 613, 612, 625, 660, 732, 876, 1164, 1740, 2892, 5196, 9804, 19020, 37452, 74316, 148044, 295500, 590412, 1180236, 2359884, 4719180, 9437772, 18874956, 37749324, 75498060, 150995532, 301990476, 603980364, 1207960140, 2415919692, 4831838796 (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-1) - 2*a(n-2) for n>5. Empirical: a(n) = 9*2^(n-1) + 588 for n>3. Empirical g.f.: x*(613 - 1227*x + 15*x^2 + 9*x^3 + 2*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Dec 13 2018 EXAMPLE Some solutions for n=4: ..1..1..0..0..0....0..0..0..0..0....0..0..0..0..0....0..1..1..1..1 ..1..1..0..0..0....1..1..1..1..1....0..0..0..0..0....1..1..1..1..1 ..1..1..0..0..0....0..0..0..0..0....0..0..0..0..0....0..0..0..0..0 ..1..1..0..0..0....0..0..0..0..0....1..1..1..1..1....1..1..1..1..1 ..1..1..0..0..0....0..0..0..0..0....1..1..1..1..1....0..0..0..0..0 ..1..1..0..0..0....0..0..0..0..0....1..1..1..1..1....0..0..0..0..0 ..1..1..0..0..0....1..1..1..1..1....1..1..1..1..1....1..1..1..1..1 ..1..1..0..0..1....0..0..0..0..0....0..0..0..0..0....1..1..1..1..1 CROSSREFS Row 7 of A253435. Sequence in context: A151592 A292036 A253434 * A253158 A159641 A100364 Adjacent sequences:  A253438 A253439 A253440 * A253442 A253443 A253444 KEYWORD nonn AUTHOR R. H. Hardin, Dec 31 2014 STATUS approved

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Last modified January 20 01:18 EST 2022. Contains 350467 sequences. (Running on oeis4.)