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A240637 Number of n X 2 0..3 arrays with no element equal to one or three horizontal or vertical neighbors, with new values 0..3 introduced in row major order. 2
1, 5, 27, 193, 1391, 10072, 72941, 528283, 3826157, 27711478, 200704271, 1453628917, 10528111931, 76251331828, 552260998337, 3999827976463, 28969316843801, 209814352850962, 1519609968699971, 11005988987858473 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A240642.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 6*a(n-1) + 10*a(n-2) - 6*a(n-3) - 9*a(n-4) for n>6.

Empirical g.f.: x*(1 - x - 13*x^2 - 13*x^3 + 2*x^4 + 3*x^5) / ((1 - x)*(1 + x)*(1 - 6*x - 9*x^2)). - Colin Barker, Mar 19 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A240642.

Sequence in context: A205774 A326094 A232683 * A023811 A126119 A105631

Adjacent sequences:  A240634 A240635 A240636 * A240638 A240639 A240640

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 09 2014

STATUS

approved

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Last modified May 29 16:43 EDT 2020. Contains 334704 sequences. (Running on oeis4.)