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A233240 Number of 2 X n 0..5 arrays with no element x(i,j) adjacent to value 5-x(i,j) horizontally, diagonally or antidiagonally, top left element zero, and 1 appearing before 2 3 and 4, and 2 appearing before 3 in row major order. 1
3, 19, 271, 4504, 79201, 1419889, 25622596, 463384804, 8386411051, 151815188839, 2748457460746, 49759306786354, 900872721644401, 16309994546050789, 295287194569964896, 5346081195735699904, 96789118201657881751 (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) = 23*a(n-1) - 81*a(n-2) - 143*a(n-3) + 82*a(n-4) + 120*a(n-5) for n>6.

Empirical g.f.: x*(3 - 50*x + 77*x^2 + 239*x^3 + 31*x^4 - 75*x^5) / ((1 - x)*(1 + x)*(1 - 6*x)*(1 - 17*x - 20*x^2)). - Colin Barker, Oct 10 2018

EXAMPLE

Some solutions for n=5:

..0..1..2..0..4....0..1..2..1..0....0..0..1..2..5....0..1..1..2..2

..0..1..2..4..2....1..0..3..0..0....1..3..1..2..5....5..3..1..5..2

CROSSREFS

Row 2 of A233239.

Sequence in context: A305562 A356672 A316294 * A173799 A003011 A338772

Adjacent sequences:  A233237 A233238 A233239 * A233241 A233242 A233243

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 06 2013

STATUS

approved

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Last modified October 3 02:59 EDT 2022. Contains 357230 sequences. (Running on oeis4.)