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 A231951 Number of (n+1) X (2+1) 0..1 arrays with every element equal to some horizontal, vertical, diagonal or antidiagonal neighbor, with top left element zero. 1
 18, 142, 1034, 7756, 58350, 438540, 3295580, 24766738, 186126146, 1398767358, 10511956032, 78999000742, 593689902080, 4461672883324, 33530172645330, 251984515016934, 1893703217109050, 14231477177253100, 106951786751372582 (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) = 7*a(n-1) + 2*a(n-2) + 13*a(n-3) + 8*a(n-4). Empirical g.f.: 2*x*(9 + 8*x + 2*x^2) / (1 - 7*x - 2*x^2 - 13*x^3 - 8*x^4). - Colin Barker, Oct 01 2018 EXAMPLE Some solutions for n=5: ..0..1..1....0..1..0....0..1..1....0..0..1....0..0..0....0..0..0....0..0..1 ..0..1..0....0..0..1....1..0..1....0..1..0....1..0..0....1..0..1....1..1..0 ..0..1..0....1..0..0....1..1..0....0..1..1....1..1..0....1..1..1....0..0..0 ..0..0..1....1..1..1....1..0..1....0..1..0....1..0..1....1..0..1....0..0..1 ..1..0..1....1..0..0....1..0..0....1..0..0....0..1..0....1..0..0....1..0..1 ..1..1..0....1..1..0....0..0..0....0..1..0....1..0..1....1..1..0....1..0..0 CROSSREFS Column 2 of A231957. Sequence in context: A299723 A125355 A299834 * A126513 A232820 A143992 Adjacent sequences: A231948 A231949 A231950 * A231952 A231953 A231954 KEYWORD nonn AUTHOR R. H. Hardin, Nov 15 2013 STATUS approved

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Last modified November 29 03:18 EST 2022. Contains 358422 sequences. (Running on oeis4.)