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A234789 Number of (n+1) X (1+1) 0..3 arrays with each 2 X 2 subblock having the number of clockwise edge increases less than or equal to the number of counterclockwise edge increases. 1
204, 2504, 30536, 371976, 4530424, 55175944, 671983416, 8184025736, 99672501944, 1213902270984, 14784004509496, 180053035925896, 2192849421966264, 26706512126351624, 325256163423006776, 3961265003235768456 (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) = 15*a(n-1) - 36*a(n-2) + 20*a(n-3).

Conjectures from Colin Barker, Oct 16 2018: (Start)

G.f.: 4*x*(51 - 139*x + 80*x^2) / ((1 - 2*x)*(1 - 13*x + 10*x^2)).

a(n) = (1/129)*2^(-1-n)*(-129*2^(1+2*n) + (2193-191*sqrt(129))*(13-sqrt(129))^n + (13+sqrt(129))^n*(2193+191*sqrt(129))).

(End)

EXAMPLE

Some solutions for n=3:

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

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

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

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

CROSSREFS

Column 1 of A234796.

Sequence in context: A249285 A292346 A234796 * A099105 A253680 A209790

Adjacent sequences:  A234786 A234787 A234788 * A234790 A234791 A234792

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2013

STATUS

approved

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Last modified April 23 09:35 EDT 2019. Contains 322385 sequences. (Running on oeis4.)