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A239040 Number of n X 1 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of elements above it, modulo 4. 3
3, 7, 16, 38, 90, 212, 500, 1180, 2784, 6568, 15496, 36560, 86256, 203504, 480128, 1132768, 2672544, 6305344, 14876224, 35097536, 82805760, 195363968, 460923008, 1087457536, 2565643008, 6053132032, 14281179136, 33693644288, 79493552640 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A239047.

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.: x*(3 + x + 2*x^2) / (1 - 2*x - 2*x^3). - Colin Barker, Feb 24 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

CROSSREFS

Cf. A239047.

Sequence in context: A192665 A052967 A297498 * A323225 A293065 A211278

Adjacent sequences:  A239037 A239038 A239039 * A239041 A239042 A239043

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 09 2014

STATUS

approved

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Last modified September 16 06:21 EDT 2019. Contains 327090 sequences. (Running on oeis4.)