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 A251221 Number of (n+1) X (1+1) 0..1 arrays with no 2 X 2 subblock having the minimum of its diagonal elements greater than the absolute difference of its antidiagonal elements. 3
 14, 49, 171, 597, 2084, 7275, 25396, 88654, 309479, 1080349, 3771351, 13165272, 45958169, 160433700, 560052166, 1955065729, 6824867819, 23824682749, 83168718156, 290330652147, 1013504710004, 3538006716150, 12350698916311 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 1 of A251228. 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) - a(n-3). Empirical g.f.: x*(14 + 7*x - 4*x^2) / (1 - 3*x - 2*x^2 + x^3). - Colin Barker, Feb 25 2018 EXAMPLE Some solutions for n=4: ..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0....1..0 ..1..0....0..1....1..1....0..0....0..1....1..0....0..0....0..1....0..0....0..0 ..1..0....0..0....0..0....0..1....1..1....1..0....0..0....0..1....1..0....0..1 ..0..0....0..0....0..0....0..1....0..1....1..1....0..1....0..0....1..1....1..0 ..1..0....0..0....1..0....1..1....0..0....0..0....1..1....0..0....1..0....1..0 CROSSREFS Cf. A251228. Sequence in context: A043943 A308834 A084049 * A302467 A303249 A215569 Adjacent sequences: A251218 A251219 A251220 * A251222 A251223 A251224 KEYWORD nonn AUTHOR R. H. Hardin, Nov 30 2014 STATUS approved

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Last modified November 30 04:37 EST 2022. Contains 358431 sequences. (Running on oeis4.)