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A221757 Number of 3 X n arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without move-in move-out straight through or left turns. 1
0, 4, 0, 43, 44, 736, 1680, 14548, 47314, 307629, 1201506, 6768794, 29159864, 152481584, 692301668, 3481342319, 16253985408, 80073291120, 379418253880, 1849109113064, 8830193356854, 42791854403241, 205182113819686 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 3 of A221755.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..73

FORMULA

Empirical: a(n) = 27*a(n-2) + 14*a(n-3) - 165*a(n-4) - 20*a(n-5) + 329*a(n-6) - 48*a(n-7) - 131*a(n-8) - 34*a(n-9) + 9*a(n-10).

Empirical g.f.: x^2*(4 - 65*x^2 - 12*x^3 + 235*x^4 - 30*x^5 - 161*x^6 - 38*x^7 + 10*x^8) / (1 - 27*x^2 - 14*x^3 + 165*x^4 + 20*x^5 - 329*x^6 + 48*x^7 + 131*x^8 + 34*x^9 - 9*x^10). - Colin Barker, Aug 10 2018

EXAMPLE

Some solutions for n=4:

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

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

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

CROSSREFS

Cf. A221755.

Sequence in context: A271834 A138546 A019217 * A189424 A009371 A248952

Adjacent sequences:  A221754 A221755 A221756 * A221758 A221759 A221760

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 24 2013

STATUS

approved

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Last modified January 18 11:50 EST 2019. Contains 319271 sequences. (Running on oeis4.)