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A232951 Number of n X 4 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally, diagonally or antidiagonally, and top left element zero. 1
27, 771, 22971, 685251, 20442651, 609853251, 18193384251, 542752261251, 16191600916251, 483034266181251, 14410069980856251, 429886928094781251, 12824557492939156251, 382587290147700781251, 11413495916966327656251 (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) = 31*a(n-1) - 35*a(n-2) + 5*a(n-3).

Conjectures from Colin Barker, Oct 06 2018: (Start)

G.f.: 3*x*(9 - 22*x + 5*x^2) / ((1 - x)*(1 - 30*x + 5*x^2)).

a(n) = (55 + (15-2*sqrt(55))^n*(55+sqrt(55)) - (-55+sqrt(55))*(15+2*sqrt(55))^n)/55.

(End)

EXAMPLE

Some solutions for n=3:

..0..0..0..1....0..2..3..1....0..2..3..2....0..0..1..1....0..2..2..2

..0..0..0..2....0..1..0..2....0..2..3..2....2..0..1..3....3..2..2..2

..0..0..0..1....0..2..3..2....0..2..3..1....1..3..2..0....0..2..0..0

CROSSREFS

Column 4 of A232955.

Sequence in context: A284039 A159668 A158645 * A138979 A183505 A218717

Adjacent sequences:  A232948 A232949 A232950 * A232952 A232953 A232954

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 02 2013

STATUS

approved

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Last modified April 7 14:29 EDT 2020. Contains 333305 sequences. (Running on oeis4.)