A202909 Number of nX1 0..7 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor

1, 8, 64, 372, 1856, 9052, 45648, 235538, 1215616, 6233356, 31868448, 163014678, 834763824, 4276077566, 21900661172, 112149148911, 574278200480, 2940790043388, 15059692639376, 77120252989206, 394927990211792

Offset

1,2

Comments

Column 1 of A202916

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -28*a(n-2) +84*a(n-3) -126*a(n-4) +252*a(n-5) -210*a(n-6) +330*a(n-7) -165*a(n-8) +220*a(n-9) -66*a(n-10) +78*a(n-11) -13*a(n-12) +14*a(n-13) -a(n-14) +a(n-15)

Example

Some solutions for n=4
..2....0....2....3....6....4....6....2....7....4....6....2....1....6....4....3
..6....5....2....3....6....7....6....3....7....4....6....6....4....7....4....3
..6....5....3....4....3....7....5....7....2....7....5....6....4....7....0....1
..4....2....3....4....0....3....0....7....0....7....2....2....0....0....0....0

Crossrefs

Sequence in context: A224151 A225014 A228460 * A203437 A224132 A297376

Adjacent sequences: A202906 A202907 A202908 * A202910 A202911 A202912

Keyword

nonn

Author

R. H. Hardin Dec 26 2011

Status

approved