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A268968 Number of n X 5 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once. 1

%I #8 Jan 17 2019 09:20:03

%S 144,3312,63792,1125360,18852912,305242992,4823705520,74858700528,

%T 1145496747312,17332683832944,259866681636528,3866483993274864,

%U 57157824214772784,840294622720295280,12294351113071353264

%N Number of n X 5 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.

%H R. H. Hardin, <a href="/A268968/b268968.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 30*a(n-1) - 261*a(n-2) + 540*a(n-3) - 324*a(n-4).

%F Empirical g.f.: 144*x*(1 - 7*x + 14*x^2 - 12*x^3) / (1 - 15*x + 18*x^2)^2. - _Colin Barker_, Jan 17 2019

%e Some solutions for n=3:

%e ..0..1..2..0..1. .0..2..2..2..1. .1..0..1..0..0. .0..2..1..0..1

%e ..2..2..1..0..0. .2..2..1..0..0. .1..0..0..1..0. .1..0..1..2..2

%e ..1..0..0..1..2. .1..0..0..0..1. .2..1..0..1..0. .1..2..2..1..0

%Y Column 5 of A268971.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 16 2016

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)