

A251344


Number of (n+1) X (1+1) 0..2 arrays with every 2 X 2 subblock summing to 3 4 or 5.


1



51, 309, 1899, 11709, 72243, 445797, 2751003, 16976493, 104762403, 646491861, 3989520459, 24619449501, 151927356051, 937548239301, 5785638109947, 35703345104973, 220326406088067, 1359640814523957, 8390383964148267
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OFFSET

1,1


LINKS



FORMULA

Empirical: a(n) = 6*a(n1) + 3*a(n2)  12*a(n3).
Empirical g.f.: 3*x*(17 + x  36*x^2) / (1  6*x  3*x^2 + 12*x^3).  Colin Barker, Nov 29 2018


EXAMPLE

Some solutions for n=4:
..1..1....0..0....1..1....1..0....1..2....2..1....0..2....1..2....2..1....0..0
..1..0....1..2....1..1....1..1....0..1....0..1....1..0....2..0....2..0....2..2
..2..0....2..0....1..2....1..1....1..2....2..0....2..0....1..0....0..2....1..0
..0..1....0..2....0..1....1..1....2..0....2..0....1..2....2..1....2..1....2..0
..2..2....2..0....2..2....2..0....1..0....0..2....0..1....2..0....0..0....2..1


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



