A251230 Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock summing to 6 and no 2 X 2 subblock having exactly two nonzero entries.

110, 270, 694, 1870, 5194, 14786, 42850, 125934, 374166, 1121566, 3386570, 10289714, 31434338, 96493518, 297491174, 920787166, 2860264522, 8914266818, 27866446818, 87355159854, 274542478518, 864878298334, 2730499054218

Offset

1,1

Links

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

Formula

Empirical: a(n) = 11*a(n-1) - 42*a(n-2) + 49*a(n-3) + 69*a(n-4) - 184*a(n-5) + 18*a(n-6) + 160*a(n-7) - 32*a(n-8) - 48*a(n-9).

Empirical g.f.: 2*x*(55 - 470*x + 1172*x^2 + 93*x^3 - 3524*x^4 + 1898*x^5 + 3268*x^6 - 1352*x^7 - 1200*x^8) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - x - x^2)*(1 - 2*x - 2*x^2)*(1 - 2*x - 4*x^2)). - Colin Barker, Nov 27 2018

Example

Some solutions for n=4:
..1..1..1....2..0..2....0..1..0....2..0..2....3..1..3....1..1..0....3..1..1
..3..1..3....2..2..2....3..2..3....2..2..2....1..1..1....2..2..3....0..2..2
..2..0..2....1..1..1....0..1..0....0..2..0....3..1..3....1..1..0....2..2..0
..1..3..1....1..3..1....3..2..3....1..3..1....1..1..1....2..2..3....0..2..2
..2..0..2....1..1..1....0..1..0....2..0..2....1..3..1....1..1..0....3..1..1

Crossrefs

Column 2 of A251236.

Sequence in context: A103652 A032614 A120727 * A264447 A134213 A028995

Adjacent sequences: A251227 A251228 A251229 * A251231 A251232 A251233

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved