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A221394
Number of n X 3 arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor, with every occupancy equal to zero or two.
1
0, 18, 0, 631, 0, 23188, 0, 852298, 0, 31322020, 0, 1151041183, 0, 42298797564, 0, 1554405335830, 0, 57121595318958, 0, 2099115475346705, 0, 77138701114715724, 0, 2834707878337590102, 0, 104170392148337357776, 0, 3828073672066667898151, 0
OFFSET
1,2
COMMENTS
Column 3 of A221396.
LINKS
FORMULA
Empirical: a(n) = 48*a(n-2) - 440*a(n-4) + 998*a(n-6) - 873*a(n-8) + 252*a(n-10) + 16*a(n-12).
Empirical g.f.: x^2*(18 - 233*x^2 + 820*x^4 - 1050*x^6 + 412*x^8 + 46*x^10) / ((1 - x)*(1 + x)*(1 - 47*x^2 + 393*x^4 - 605*x^6 + 268*x^8 + 16*x^10)). - Colin Barker, Aug 05 2018
CROSSREFS
Cf. A221396.
Sequence in context: A375681 A376444 A376442 * A025602 A088126 A040327
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 14 2013
STATUS
approved