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 A269137 Number of n X 2 0..3 arrays with some element plus some horizontally, antidiagonally or vertically adjacent neighbor totalling three no more than once. 1
 16, 148, 1164, 8532, 59916, 408596, 2727564, 17914580, 116170764, 745617300, 4745165964, 29984668756, 188330955276, 1176750424852, 7319499656844, 45347466532308, 279961285570572, 1722988944076436, 10574188575966348 (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) = 12*a(n-1) - 38*a(n-2) + 12*a(n-3) - a(n-4) for n>5. Empirical g.f.: 4*x*(4 - 11*x - x^2 - x^3 + x^4) / (1 - 6*x + x^2)^2. - Colin Barker, Jan 19 2019 EXAMPLE Some solutions for n=4: ..2..0. .3..3. .1..0. .2..2. .3..0. .2..1. .0..0. .0..1. .3..3. .0..1 ..2..2. .1..1. .1..1. .2..3. .1..0. .0..1. .0..1. .0..0. .1..1. .0..3 ..3..1. .1..3. .3..1. .0..1. .0..1. .1..1. .1..1. .1..2. .1..1. .1..1 ..1..1. .3..3. .0..0. .0..1. .0..0. .3..1. .0..2. .0..2. .3..0. .1..0 CROSSREFS Column 2 of A269143. Sequence in context: A214513 A254952 A178259 * A155657 A135458 A000486 Adjacent sequences:  A269134 A269135 A269136 * A269138 A269139 A269140 KEYWORD nonn AUTHOR R. H. Hardin, Feb 20 2016 STATUS approved

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Last modified June 18 10:54 EDT 2021. Contains 345098 sequences. (Running on oeis4.)