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A198648
Number of n X 1 0..6 arrays with values 0..6 introduced in row major order and each element equal to at least one horizontal or vertical neighbor.
2
0, 1, 1, 2, 3, 6, 11, 23, 47, 103, 226, 518, 1200, 2867, 6946, 17233, 43385, 111354, 289861, 766767, 2054605, 5579891, 15325432, 42559486, 119312586, 337469019, 961850000, 2760643085, 7971239103, 23140321458, 67486362815, 197615025815
OFFSET
1,4
COMMENTS
Column 1 of A198654.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) +a(n-2) -60*a(n-3) +50*a(n-4) +226*a(n-5) -231*a(n-6) -416*a(n-7) +361*a(n-8) +388*a(n-9) -180*a(n-10) -144*a(n-11) for n>12.
Empirical g.f.: x^2*(1 - 5*x - 5*x^2 + 50*x^3 - 4*x^4 - 184*x^5 + 36*x^6 + 303*x^7 - 3*x^8 - 189*x^9 - 53*x^10) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 + 2*x)*(1 - 3*x)*(1 - x - x^2)*(1 - x - 3*x^2)*(1 - x - 4*x^2)). - Colin Barker, May 15 2018
EXAMPLE
All solutions for n=5:
..0....0....0
..0....0....0
..0....0....1
..1....0....1
..1....0....1
CROSSREFS
Cf. A198654.
Sequence in context: A277795 A198662 A198620 * A198655 A211694 A303586
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 28 2011
STATUS
approved