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A239851 Number of n X 1 0..3 arrays with no element equal to zero plus the sum of elements to its left or zero plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4. 10
2, 2, 4, 6, 8, 14, 20, 30, 48, 70, 108, 166, 248, 382, 580, 878, 1344, 2038, 3100, 4726, 7176, 10926, 16628, 25278, 38480, 58534, 89036, 135494, 206104, 313566, 477092, 725774, 1104224, 1679958, 2555772, 3888406, 5915688, 8999950, 13692500 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A239858.

LINKS

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

FORMULA

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

Empirical g.f.: 2*x*(1 + x + x^2) / (1 - x^2 - 2*x^3). - Colin Barker, Feb 18 2018

EXAMPLE

All solutions for n=4:

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

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

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

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

CROSSREFS

Sequence in context: A266949 A255710 A329137 * A153958 A216214 A269298

Adjacent sequences:  A239848 A239849 A239850 * A239852 A239853 A239854

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 28 2014

STATUS

approved

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Last modified August 7 23:53 EDT 2020. Contains 336280 sequences. (Running on oeis4.)