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 A269291 Number of 3 X n 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three no more than once. 1
 64, 2592, 62748, 1363572, 27788292, 544118148, 10363900428, 193439931300, 3554908340004, 64533455294868, 1159917367905324, 20677732339697748, 366084589527655236, 6443257191283855908, 112830460117748363340 (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) = 36*a(n-1) - 378*a(n-2) + 972*a(n-3) - 729*a(n-4) for n>7. Empirical g.f.: 4*x*(16 + 72*x - 1593*x^2 + 5553*x^3 - 13581*x^4 + 17091*x^5 - 6804*x^6) / (1 - 18*x + 27*x^2)^2. - Colin Barker, Jan 21 2019 EXAMPLE Some solutions for n=3: ..0..0..0. .1..1..0. .3..2..0. .1..1..3. .1..0..0. .1..3..3. .1..3..3 ..2..0..2. .3..0..1. .2..0..2. .1..1..0. .0..2..0. .1..1..1. .3..3..0 ..1..1..0. .1..1..0. .3..2..0. .1..1..0. .3..0..2. .1..3..3. .1..1..1 CROSSREFS Row 3 of A269289. Sequence in context: A240363 A239432 A004388 * A203256 A265632 A144843 Adjacent sequences:  A269288 A269289 A269290 * A269292 A269293 A269294 KEYWORD nonn AUTHOR R. H. Hardin, Feb 21 2016 STATUS approved

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Last modified July 30 07:41 EDT 2021. Contains 346348 sequences. (Running on oeis4.)