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 A221236 Number of n X 2 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without 2-loops. 1
 0, 5, 53, 467, 3913, 32299, 265353, 2176758, 17847997, 146319703, 1199485661, 9832876386, 80605364957, 660764392260, 5416629053076, 44402915641056, 363993693602517, 2983844751876537, 24460120087308763, 200512266365651825 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 2 of A221240. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 11*a(n-1) - 23*a(n-2) - a(n-3) + 10*a(n-4) - a(n-6). Empirical g.f.: x^2*(5 - 2*x - x^2) / ((1 - 3*x + x^2)*(1 - 8*x - 2*x^2 + 3*x^3 + x^4)). - Colin Barker, Aug 04 2018 EXAMPLE Some solutions for n=3: ..1..0....0..0....1..1....0..2....1..1....0..1....1..1....0..2....0..2....0..1 ..2..1....2..1....1..3....1..1....1..2....3..2....2..0....2..2....1..3....0..3 ..2..0....2..1....0..0....1..1....1..0....0..0....2..0....0..0....0..0....1..1 CROSSREFS Cf. A221240. Sequence in context: A069617 A173879 A058390 * A198963 A293082 A069592 Adjacent sequences: A221233 A221234 A221235 * A221237 A221238 A221239 KEYWORD nonn AUTHOR R. H. Hardin, Jan 06 2013 STATUS approved

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Last modified October 1 11:49 EDT 2023. Contains 365826 sequences. (Running on oeis4.)