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 A268784 Number of n X 3 binary arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two exactly once. 1
 2, 17, 72, 302, 1144, 4207, 14984, 52335, 179854, 610504, 2051436, 6836258, 22622554, 74418562, 243553160, 793537401, 2575357784, 8329124488, 26854438804, 86342760711, 276915214344, 886094782671, 2829527431748, 9018299661270 (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) = 2*a(n-1) + 9*a(n-2) - 2*a(n-3) - 33*a(n-4) - 42*a(n-5) - 14*a(n-6) + 10*a(n-7) + 8*a(n-8) - a(n-10). Empirical g.f.: x*(2 + 13*x + 20*x^2 + 9*x^3 - 8*x^4 - 10*x^5 - 4*x^6) / ((1 + x)^2*(1 - 2*x - 3*x^2 - x^3 + x^4)^2). - Colin Barker, Jan 15 2019 EXAMPLE Some solutions for n=4: ..1..0..1. .1..1..0. .1..0..0. .0..1..0. .1..0..0. .0..0..1. .1..0..1 ..0..1..0. .0..0..1. .0..0..1. .0..0..0. .1..0..1. .1..0..1. .0..1..0 ..0..0..0. .0..0..0. .1..0..0. .1..0..0. .0..0..0. .0..0..0. .0..0..1 ..1..0..0. .0..0..0. .1..0..0. .1..0..1. .0..1..0. .1..0..0. .0..0..0 CROSSREFS Column 3 of A268789. Sequence in context: A182876 A056074 A320685 * A338088 A155715 A307851 Adjacent sequences: A268781 A268782 A268783 * A268785 A268786 A268787 KEYWORD nonn AUTHOR R. H. Hardin, Feb 13 2016 STATUS approved

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Last modified September 26 15:54 EDT 2023. Contains 365660 sequences. (Running on oeis4.)