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 A196423 Number of n X 1 0..4 arrays with each element equal to the number its horizontal and vertical neighbors less than itself. 5
 1, 3, 5, 11, 26, 55, 119, 263, 573, 1248, 2729, 5959, 13005, 28399, 62010, 135383, 295595, 645407, 1409161, 3076736, 6717713, 14667339, 32024421, 69921635, 152665786, 333328023, 727783135, 1589030151, 3469463141, 7575170720 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 1 of A196430. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n) = a(n-1) +a(n-2) +3*a(n-3) +a(n-4). Empirical: G.f. -x*(1+x)^2 / ( -1+x+x^2+3*x^3+x^4 ). - R. J. Mathar, Jul 25 2012 EXAMPLE All solutions for n=3: ..0....1....0....0....1 ..0....0....2....0....0 ..0....0....0....1....1 CROSSREFS Cf. A196430. Sequence in context: A027050 A240148 A109249 * A320177 A289468 A289534 Adjacent sequences: A196420 A196421 A196422 * A196424 A196425 A196426 KEYWORD nonn AUTHOR R. H. Hardin, Oct 02 2011 STATUS approved

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Last modified September 7 19:14 EDT 2024. Contains 375749 sequences. (Running on oeis4.)