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A198976 Number of n X 2 0..5 arrays with values 0..5 introduced in row major order and no element equal to any horizontal or vertical neighbor. 3
1, 4, 34, 481, 8731, 174454, 3603244, 75251971, 1577395861, 33105096904, 695065679254, 14595390246661, 306496273473391, 6436373295247354, 135163500079092064, 2838431127851480551, 59607037068329713321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A198982.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 32*a(n-1) - 262*a(n-2) + 672*a(n-3) - 441*a(n-4).

Conjectures from Colin Barker, Feb 22 2018: (Start)

G.f.: x*(1 - 28*x + 168*x^2 - 231*x^3) / ((1 - x)*(1 - 3*x)*(1 - 7*x)*(1 - 21*x)).

a(n) = (189 + 56*3^n + 18*7^n + 21^n) / 504.

(End)

EXAMPLE

Some solutions with all values from 0 to 5 for n=4:

..0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1

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

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

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

CROSSREFS

Cf. A198982.

Sequence in context: A193099 A208831 A294475 * A156325 A248654 A336495

Adjacent sequences:  A198973 A198974 A198975 * A198977 A198978 A198979

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 01 2011

STATUS

approved

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Last modified May 22 09:50 EDT 2022. Contains 353949 sequences. (Running on oeis4.)