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A239812 Number of n X 1 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of elements above it, modulo 4. 4
2, 5, 11, 25, 57, 129, 293, 665, 1509, 3425, 7773, 17641, 40037, 90865, 206221, 468025, 1062197, 2410689, 5471133, 12416905, 28180549, 63956625, 145151533, 329425881, 747642197, 1696797025, 3850933181, 8739811625, 19835272037, 45016761649 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A239819.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 2*a(n-2) + 2*a(n-3).

Empirical g.f.: x*(2 + 3*x + 2*x^2) / (1 - x - 2*x^2 - 2*x^3). - Colin Barker, Feb 21 2018

EXAMPLE

Some solutions for n=5:

..2....2....2....2....3....2....2....3....2....3....2....2....3....3....2....3

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

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

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

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

CROSSREFS

Cf. A239819.

Sequence in context: A106805 A094981 A304969 * A097779 A319768 A106336

Adjacent sequences:  A239809 A239810 A239811 * A239813 A239814 A239815

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 27 2014

STATUS

approved

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Last modified August 24 03:51 EDT 2019. Contains 326260 sequences. (Running on oeis4.)