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A184031 1/16 the number of (n+1) X 2 0..3 arrays with all 2 X 2 subblocks having the same four values. 1
16, 28, 49, 91, 169, 325, 625, 1225, 2401, 4753, 9409, 18721, 37249, 74305, 148225, 296065, 591361, 1181953, 2362369, 4723201, 9443329, 18883585, 37761025, 75515905, 151019521, 302026753, 604028929, 1208033281, 2416017409, 4831985665 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A184039.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) - 6*a(n-3) + 4*a(n-4).

Conjectures from Colin Barker, Apr 10 2018: (Start)

G.f.: x*(16 - 20*x - 35*x^2 + 40*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).

a(n) = 9*2^(n/2-1) + 9*2^(n-1) + 1 for n even.

a(n) = 9*2^(n-1) + 3*2^((n+1)/2) + 1 for n odd.

(End)

EXAMPLE

Some solutions for 3 X 2:

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

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

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

CROSSREFS

Cf. A184039.

Sequence in context: A280989 A337663 A211570 * A206259 A064803 A220762

Adjacent sequences:  A184028 A184029 A184030 * A184032 A184033 A184034

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 08 2011

STATUS

approved

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Last modified November 27 16:35 EST 2021. Contains 349394 sequences. (Running on oeis4.)