A221484 - OEIS

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A221484

Number of 2 X n arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without consecutive moves in the same direction.

0, 4, 8, 73, 292, 1713, 8235, 43733, 220672, 1142790, 5840082, 30047605, 154064032, 791329272, 4060908537, 20849136414, 107016685715, 549372170263, 2820041046796, 14476302849381, 74310986678816, 381462539353767

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OFFSET

1,2

COMMENTS

Row 2 of A221483.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = a(n-1) + 17*a(n-2) + 22*a(n-3) + a(n-4) - 14*a(n-5) - 2*a(n-6) + a(n-7).

Empirical g.f.: x^2*(1 - x)*(4 + 8*x + 5*x^2) / ((1 + 3*x + x^2)*(1 - 4*x - 6*x^2 + 5*x^4 - x^5)). - Colin Barker, Aug 06 2018

EXAMPLE

Some solutions for n=3: