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A239333 Number of n X 1 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of elements above it, modulo 4. 9
2, 5, 12, 28, 66, 156, 368, 868, 2048, 4832, 11400, 26896, 63456, 149712, 353216, 833344, 1966112, 4638656, 10944000, 25820224, 60917760, 143723520, 339087488, 800010496, 1887468032, 4453111040, 10506243072, 24787422208, 58481066496 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A239340.

LINKS

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

FORMULA

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

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

EXAMPLE

Some solutions for n=5:

..0....2....2....2....0....0....0....0....2....2....2....2....2....0....2....2

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

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

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

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

CROSSREFS

Sequence in context: A209173 A297496 A302020 * A255115 A166297 A024960

Adjacent sequences:  A239330 A239331 A239332 * A239334 A239335 A239336

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 16 2014

STATUS

approved

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Last modified April 5 10:28 EDT 2020. Contains 333239 sequences. (Running on oeis4.)