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 A221777 Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal, diagonal or antidiagonal neighbor, without move-in move-out left turns. 2

%I #9 Mar 14 2018 12:20:55

%S 3,25,184,1367,10179,75782,564169,4200043,31267890,232778781,

%T 1732958641,12901286112,96045675555,715027301353,5323134422488,

%U 39628920498935,295023799000179,2196351575583206,16351088488165993,121728277803994939

%N Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal, diagonal or antidiagonal neighbor, without move-in move-out left turns.

%C Column 2 of A221780.

%H R. H. Hardin, <a href="/A221777/b221777.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 8*a(n-1) - 5*a(n-2) + 7*a(n-3) - 4*a(n-4) - a(n-5).

%F Empirical g.f.: x*(3 + x - x^2 - x^3) / ((1 + x^2)*(1 - 8*x + 4*x^2 + x^3)). - _Colin Barker_, Mar 14 2018

%e Some solutions for n=3:

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

%e ..1..3....1..2....1..2....2..1....2..2....2..2....1..2....1..2....0..0....0..3

%e ..0..0....0..2....0..0....3..0....0..0....0..0....0..1....1..0....2..2....2..0

%Y Cf. A221780.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 25 2013

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Last modified August 14 09:16 EDT 2024. Contains 375159 sequences. (Running on oeis4.)