A203184 Number of nX1 0..4 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor

1, 5, 25, 95, 325, 1121, 3985, 14288, 50995, 181336, 644721, 2294193, 8166441, 29066618, 103444256, 368138471, 1310164527, 4662787112, 16594519920, 59058487061, 210183969235, 748026706926, 2662163892493, 9474416502527

Offset

1,2

Comments

Column 1 of A203191

Links

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

Formula

Empirical: a(n) = 5*a(n-1) -10*a(n-2) +20*a(n-3) -15*a(n-4) +21*a(n-5) -7*a(n-6) +8*a(n-7) -a(n-8) +a(n-9).

Empirical g.f.: -x*(1+x^2)*(x^6+6*x^4+9*x^2+1) / ( -1+5*x-10*x^2+20*x^3-15*x^4+21*x^5-7*x^6+8*x^7-x^8+x^9 ). - R. J. Mathar, Jul 02 2013

Example

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

Crossrefs

Sequence in context: A225011 A228457 A213293 * A073374 A126878 A203340

Adjacent sequences: A203181 A203182 A203183 * A203185 A203186 A203187

Keyword

nonn

Author

R. H. Hardin, Dec 30 2011

Status

approved