A251500 Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock summing to 3 4 5 6 7 8 or 9.

226, 3250, 46684, 670690, 9635410, 138426508, 1988695378, 28570462642, 410455690300, 5896784936386, 84715776652690, 1217063686620268, 17484866170347826, 251195190815325682, 3608779345177708828

Offset

1,1

Links

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

Formula

Empirical: a(n) = 13*a(n-1) + 21*a(n-2) - 18*a(n-3) - 24*a(n-4).

Empirical g.f.: 2*x*(113 + 156*x - 156*x^2 - 192*x^3) / (1 - 13*x - 21*x^2 + 18*x^3 + 24*x^4). - Colin Barker, Nov 29 2018

Example

Some solutions for n=3:
..0..0....2..3....3..1....2..2....2..1....2..3....0..3....2..0....0..3....3..0
..3..0....2..0....2..1....0..3....0..3....2..1....1..3....0..1....0..0....0..0
..1..3....3..0....1..1....3..3....3..0....1..3....2..0....0..3....3..3....1..3
..1..1....1..1....3..2....1..1....2..0....0..0....2..0....1..3....1..1....1..0

Crossrefs

Column 1 of A251507.

Sequence in context: A251402 A251395 A251507 * A050847 A098247 A092994

Adjacent sequences: A251497 A251498 A251499 * A251501 A251502 A251503

Keyword

nonn

Author

R. H. Hardin, Dec 03 2014

Status

approved