A269291 Number of 3 X n 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three no more than once.

64, 2592, 62748, 1363572, 27788292, 544118148, 10363900428, 193439931300, 3554908340004, 64533455294868, 1159917367905324, 20677732339697748, 366084589527655236, 6443257191283855908, 112830460117748363340

Offset

1,1

Links

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

Formula

Empirical: a(n) = 36*a(n-1) - 378*a(n-2) + 972*a(n-3) - 729*a(n-4) for n>7.

Empirical g.f.: 4*x*(16 + 72*x - 1593*x^2 + 5553*x^3 - 13581*x^4 + 17091*x^5 - 6804*x^6) / (1 - 18*x + 27*x^2)^2. - Colin Barker, Jan 21 2019

Example

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

Crossrefs

Row 3 of A269289.

Sequence in context: A240363 A239432 A004388 * A203256 A265632 A144843

Adjacent sequences: A269288 A269289 A269290 * A269292 A269293 A269294

Keyword

nonn

Author

R. H. Hardin, Feb 21 2016

Status

approved