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A270053
Number of nX3 0..4 arrays with some element plus some horizontally or vertically adjacent neighbor totalling four exactly once.
1
40, 5400, 385200, 22911300, 1248460920, 64599504300, 3230189811360, 157641639369300, 7554828673749960, 356991331281723900, 16680284779615323120, 772247380917124520100, 35480193258896640581400
OFFSET
1,1
COMMENTS
Column 3 of A270058.
LINKS
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: A378234 A259461 A229692 * A123810 A275655 A146198
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 09 2016
STATUS
approved