A317818 Number of nX3 0..1 arrays with every element unequal to 1, 2 or 3 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

1, 16, 35, 135, 356, 1113, 3150, 9484, 27522, 81798, 239572, 707803, 2080838, 6134691, 18056895, 53200116, 156648460, 461423021, 1358857346, 4002288009, 11787108436, 34715792064, 102243257032, 301126862896, 886870040361

Offset

1,2

Comments

Column 3 of A317823.

Links

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

Formula

Empirical: a(n) = a(n-1) +7*a(n-2) +2*a(n-3) -10*a(n-4) -14*a(n-5) -16*a(n-6) -25*a(n-7) +36*a(n-8) +42*a(n-9) -26*a(n-10) +62*a(n-11) +10*a(n-12) -28*a(n-13) +20*a(n-14) -16*a(n-15) +4*a(n-16) for n>18

Example

Some solutions for n=5
..0..1..1. .0..1..1. .0..1..0. .0..0..1. .0..0..1. .0..1..0. .0..0..0
..1..0..0. .1..0..0. .1..0..0. .1..0..0. .1..0..0. .1..0..1. .1..1..1
..0..0..1. .0..0..1. .0..1..1. .1..0..0. .1..0..1. .0..0..1. .0..1..1
..1..1..1. .0..1..0. .1..1..0. .0..0..1. .0..1..1. .0..0..1. .0..1..0
..0..0..0. .1..1..0. .0..0..1. .0..1..0. .1..0..0. .1..0..0. .0..1..0

Crossrefs

Cf. A317823.

Sequence in context: A105509 A337024 A219316 * A236463 A070588 A250432

Adjacent sequences: A317815 A317816 A317817 * A317819 A317820 A317821

Keyword

nonn

Author

R. H. Hardin, Aug 07 2018

Status

approved