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 A220939 Number of n X 2 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor. 1
 1, 20, 208, 2056, 20483, 203905, 2029453, 20199560, 201050056, 2001087460, 19917184799, 198239333473, 1973111833705, 19638737859212, 195467898964096, 1945527242870032, 19364183442340907, 192735209316410785 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 2 of A220943. LINKS R. H. Hardin, Table of n, a(n) for n = 1..83 FORMULA Empirical: a(n) = 13*a(n-1) - 32*a(n-2) + 22*a(n-3) - 62*a(n-4) + 92*a(n-5) - 33*a(n-6) + a(n-7). Empirical g.f.: x*(1 + 7*x - 20*x^2 - 30*x^3 + 33*x^4 - 10*x^5 + x^6) / ((1 - x)*(1 - 12*x + 20*x^2 - 2*x^3 + 60*x^4 - 32*x^5 + x^6)). - Colin Barker, Aug 03 2018 EXAMPLE Some solutions for n=3: ..0..1....2..0....0..1....1..1....1..2....0..1....1..2....1..2....0..1....2..1 ..1..2....3..1....2..2....1..0....2..1....2..3....0..2....0..3....0..2....2..0 ..2..0....0..0....1..0....3..0....0..0....0..0....1..0....0..0....2..1....1..0 CROSSREFS Cf. A220943. Sequence in context: A325474 A133070 A135179 * A231059 A161513 A162359 Adjacent sequences: A220936 A220937 A220938 * A220940 A220941 A220942 KEYWORD nonn AUTHOR R. H. Hardin, Dec 25 2012 STATUS approved

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Last modified February 4 23:12 EST 2023. Contains 360082 sequences. (Running on oeis4.)