A221570 Number of 0..5 arrays of length n with each element differing from at least one neighbor by something other than 1

0, 26, 114, 676, 3734, 20944, 117104, 655198, 3665306, 20505052, 114711980, 641737294, 3590092664, 20084178100, 112357602542, 628565969692, 3516408049766, 19671961528672, 110051525562128, 615665004273436

Offset

1,2

Comments

Column 5 of A221573

Links

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

Formula

Empirical: a(n) = 5*a(n-1) +3*a(n-2) +9*a(n-4) +6*a(n-5) +3*a(n-6).

Empirical g.f.: -2*x^2*(13-8*x+14*x^2+6*x^3+6*x^4) / ( -1+5*x+3*x^2+9*x^4+6*x^5+3*x^6 ). - R. J. Mathar, Jun 06 2013

Example

Some solutions for n=6
..4....0....4....1....2....5....4....4....2....0....0....1....1....3....0....3
..0....5....2....3....4....2....0....4....5....3....5....4....3....5....3....5
..0....2....4....5....0....5....0....0....4....5....0....1....0....2....0....1
..1....5....5....3....1....4....2....3....1....4....3....2....1....4....3....3
..3....1....0....1....4....1....1....1....0....2....2....2....5....2....0....3
..1....5....5....5....0....3....4....5....4....0....2....4....3....5....0....1

Crossrefs

Sequence in context: A262476 A156385 A251262 * A100161 A100162 A051729

Adjacent sequences: A221567 A221568 A221569 * A221571 A221572 A221573

Keyword

nonn

Author

R. H. Hardin Jan 20 2013

Status

approved