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 A268990 Number of n X 3 binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once. 1
 7, 35, 174, 849, 4083, 19416, 91491, 427863, 1988142, 9187653, 42256599, 193542240, 883204143, 4017241083, 18219040206, 82410172617, 371879874987, 1674499435176, 7525052043819, 33755742643791, 151168877259918, 675941817039645 (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) = 10*a(n-1) - 31*a(n-2) + 30*a(n-3) - 9*a(n-4). Empirical g.f.: x*(7 - 35*x + 41*x^2 - 16*x^3) / (1 - 5*x + 3*x^2)^2. - Colin Barker, Jan 17 2019 EXAMPLE Some solutions for n=4: ..1..1..0. .0..0..1. .0..0..1. .0..0..0. .1..1..0. .0..1..0. .1..0..0 ..0..1..0. .1..0..0. .1..0..0. .0..0..1. .0..0..0. .0..0..1. .1..0..0 ..0..0..0. .0..0..1. .1..0..0. .0..0..0. .0..0..1. .1..0..0. .1..1..0 ..1..0..1. .0..0..1. .0..1..1. .0..1..0. .0..0..1. .0..1..1. .0..1..0 CROSSREFS Column 3 of A268995. Sequence in context: A110213 A034348 A249793 * A005055 A037506 A037689 Adjacent sequences: A268987 A268988 A268989 * A268991 A268992 A268993 KEYWORD nonn AUTHOR R. H. Hardin, Feb 17 2016 STATUS approved

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Last modified July 21 20:59 EDT 2024. Contains 374475 sequences. (Running on oeis4.)