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A251230 Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock summing to 6 and no 2 X 2 subblock having exactly two nonzero entries. 1
110, 270, 694, 1870, 5194, 14786, 42850, 125934, 374166, 1121566, 3386570, 10289714, 31434338, 96493518, 297491174, 920787166, 2860264522, 8914266818, 27866446818, 87355159854, 274542478518, 864878298334, 2730499054218 (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) = 11*a(n-1) - 42*a(n-2) + 49*a(n-3) + 69*a(n-4) - 184*a(n-5) + 18*a(n-6) + 160*a(n-7) - 32*a(n-8) - 48*a(n-9).

Empirical g.f.: 2*x*(55 - 470*x + 1172*x^2 + 93*x^3 - 3524*x^4 + 1898*x^5 + 3268*x^6 - 1352*x^7 - 1200*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - x - x^2)*(1 - 2*x - 2*x^2)*(1 - 2*x - 4*x^2)). - Colin Barker, Nov 27 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 2 of A251236.

Sequence in context: A103652 A032614 A120727 * A264447 A134213 A028995

Adjacent sequences:  A251227 A251228 A251229 * A251231 A251232 A251233

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified December 14 03:31 EST 2019. Contains 329978 sequences. (Running on oeis4.)