A186162 - OEIS

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A186162

1/4 the number of nX3 0..3 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors

1, 48, 702, 14364, 253341, 4762206, 87054174, 1610684397, 29645381115, 546876640548, 10078456022415, 185816448936792, 3425262221153151, 63144918326035629, 1164039832228952691, 21458721711659114403

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Column 3 of A186168

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n)=12*a(n-1)+138*a(n-2)-297*a(n-3)-1095*a(n-4)-588*a(n-5)+4871*a(n-6)+10632*a(n-7)-24375*a(n-8)+40893*a(n-9)-59724*a(n-10)-68247*a(n-11)-358891*a(n-12)+1270395*a(n-13)+391440*a(n-14)-2188134*a(n-15)+133083*a(n-16)+1270323*a(n-17)+3453273*a(n-18)+1073817*a(n-19)-5417199*a(n-20)-4448358*a(n-21)-13463172*a(n-22)-12754584*a(n-23)

EXAMPLE

Some solutions for 4X3 with a(1,1)=0

..0..0..0....0..1..0....0..0..0....0..2..2....0..2..2....0..3..3....0..0..3

..0..3..3....0..1..0....2..2..0....0..2..3....0..3..1....0..2..2....0..1..3

..3..1..1....3..1..3....3..2..2....0..3..3....3..3..1....0..1..3....2..1..1

..3..2..2....3..1..3....3..3..3....1..1..1....1..1..1....1..1..3....2..0..0

CROSSREFS

Sequence in context: A233152 A138411 A361188 * A102279 A132464 A145155

Adjacent sequences: A186159 A186160 A186161 * A186163 A186164 A186165

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 13 2011

STATUS

approved