A270053 Number of nX3 0..4 arrays with some element plus some horizontally or vertically adjacent neighbor totalling four exactly once.

40, 5400, 385200, 22911300, 1248460920, 64599504300, 3230189811360, 157641639369300, 7554828673749960, 356991331281723900, 16680284779615323120, 772247380917124520100, 35480193258896640581400

Offset

1,1

Comments

Column 3 of A270058.

Links

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

Formula

Empirical: a(n) = 90*a(n-1) -2257*a(n-2) +10440*a(n-3) -13456*a(n-4) for n>5.

Empirical: g.f. 40*x -180*x^2*(-30+560*x-2395*x^2+2976*x^3) / (116*x^2-45*x+1)^2 . - R. J. Mathar, Mar 09 2016

Example

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

Crossrefs

Cf. A270058.

Sequence in context: A347854 A259461 A229692 * A123810 A275655 A146198

Adjacent sequences: A270050 A270051 A270052 * A270054 A270055 A270056

Keyword

nonn

Author

R. H. Hardin, Mar 09 2016

Status

approved