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A206170 Number of 2 X (n+1) 0..3 arrays with every 2 X 2 subblock in a row having an equal number of equal diagonal or equal antidiagonal elements, adjacent rows differing in this number, and new values 0..3 introduced in row major order. 2
15, 85, 641, 5257, 44585, 385465, 3375401, 29817817, 264999305, 2364834745, 21162573161, 189737549977, 1703284356425, 15303437762425, 137574211418921, 1237227532571737, 11129405572871945, 100130796836040505 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 1 of A206169.

LINKS

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

FORMULA

Empirical: a(n) = 18*a(n-1) - 101*a(n-2) + 192*a(n-3) - 108*a(n-4).

Conjectures from Colin Barker, Mar 04 2018: (Start)

G.f.: x*(15 - 185*x + 626*x^2 - 576*x^3) / ((1 - x)*(1 - 2*x)*(1 - 6*x)*(1 - 9*x)).

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

(End)

EXAMPLE

Some solutions for n=4:

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

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

CROSSREFS

Cf. A206169.

Sequence in context: A160747 A064058 A138322 * A177882 A199897 A302948

Adjacent sequences:  A206167 A206168 A206169 * A206171 A206172 A206173

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 04 2012

STATUS

approved

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Last modified March 25 08:15 EDT 2019. Contains 321469 sequences. (Running on oeis4.)