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 A269031 Number of n X 4 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two exactly once. 1
 36, 216, 2166, 18384, 146064, 1114848, 8277072, 60218112, 431354928, 3052215072, 21383561232, 148585984320, 1025363155440, 7034327057760, 48013557090768, 326276117933952, 2208609401649072, 14899002865010592, 100198549907000208 (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) = 14*a(n-1) - 57*a(n-2) + 56*a(n-3) - 16*a(n-4) for n>5. Empirical g.f.: 6*x*(6 - 48*x + 199*x^2 - 274*x^3 + 105*x^4) / (1 - 7*x + 4*x^2)^2. - Colin Barker, Jan 18 2019 EXAMPLE Some solutions for n=4: ..0..0..0..1. .1..0..0..1. .0..1..2..1. .2..1..0..0. .2..2..1..2 ..0..1..0..1. .1..0..0..0. .2..1..0..1. .2..1..0..1. .2..2..2..1 ..2..1..2..2. .0..0..1..0. .0..1..0..1. .2..1..0..1. .2..1..2..2 ..2..1..2..2. .0..1..0..0. .2..1..2..0. .2..1..2..2. .2..1..2..2 CROSSREFS Column 4 of A269035. Sequence in context: A230470 A066610 A176696 * A113164 A237252 A017234 Adjacent sequences: A269028 A269029 A269030 * A269032 A269033 A269034 KEYWORD nonn AUTHOR R. H. Hardin, Feb 18 2016 STATUS approved

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Last modified August 12 19:26 EDT 2024. Contains 375113 sequences. (Running on oeis4.)