A233921 Number of (n+1) X (1+1) 0..4 arrays with every 2 X 2 subblock having the sum of the absolute values of the edge differences equal to 8 and no adjacent elements equal.

98, 518, 2792, 15230, 83290, 456328, 2500838, 13709358, 75155340, 412023922, 2258839434, 12383734204, 67891856922, 372206825758, 2040567205064, 11187101456262, 61331590903554, 336241181497880, 1843391459226238

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) + 5*a(n-2) - 46*a(n-3) + 5*a(n-4) + 60*a(n-5) + 20*a(n-6).

Empirical g.f.: 2*x*(49 - 35*x - 403*x^2 + 198*x^3 + 644*x^4 + 200*x^5) / ((1 - 2*x)*(1 - 4*x - 13*x^2 + 20*x^3 + 35*x^4 + 10*x^5)). - Colin Barker, Oct 12 2018

Example

Some solutions for n=5:
..0..2....1..4....2..3....3..1....3..0....1..0....0..2....3..2....0..1....1..0
..3..1....0..2....4..1....0..2....2..3....2..4....4..3....0..3....3..0....0..3
..2..4....3..4....3..4....2..4....4..1....0..2....3..0....3..4....0..1....1..0
..0..3....0..1....0..2....0..2....2..0....1..4....4..1....2..0....3..0....4..3
..1..4....2..4....4..3....2..0....4..1....4..3....3..4....3..4....2..3....0..2
..0..3....4..2....1..0....4..3....2..0....1..0....0..2....0..3....0..4....4..3

Crossrefs

Column 1 of A233928.

Sequence in context: A263033 A239173 A233928 * A203083 A202370 A184608

Adjacent sequences: A233918 A233919 A233920 * A233922 A233923 A233924

Keyword

nonn

Author

R. H. Hardin, Dec 17 2013

Status

approved