A196537 Number of nX1 0..4 arrays with each element equal to the number its horizontal and vertical neighbors less than or equal to itself

1, 3, 2, 7, 19, 35, 77, 176, 377, 819, 1801, 3927, 8562, 18711, 40855, 89179, 194729, 425184, 928305, 2026855, 4425441, 9662395, 21096706, 46062279, 100571611, 219586403, 479441557, 1046805072, 2285577449, 4990293595, 10895727817

Offset

1,2

Comments

Column 1 of A196544

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

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

Empirical: G.f. x*(x-1)*(x^2+3*x+1) / ( -1+x+x^2+3*x^3+x^4 ). - R. J. Mathar, Jul 25 2012

Example

All solutions for n=4
..0....0....1....0....0....1....0
..2....1....0....2....2....1....2
..2....2....2....1....1....2....0
..0....0....0....1....0....0....1

Crossrefs

Sequence in context: A104528 A177115 A316087 * A173099 A111928 A348695

Adjacent sequences: A196534 A196535 A196536 * A196538 A196539 A196540

Keyword

nonn

Author

R. H. Hardin Oct 03 2011

Status

approved