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 A221818 Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, without move-in move-out straight through or left turns. 1
 0, 4, 16, 91, 459, 2429, 12678, 66380, 347305, 1817234, 9509123, 49756006, 260353922, 1362310931, 7128385902, 37299670925, 195172780250, 1021252966367, 5343766480365, 27961572573739, 146310575925354, 765578706008096 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = a(n-1) +17*a(n-2) +25*a(n-3) +7*a(n-4) +15*a(n-5) +10*a(n-6) -19*a(n-7) +8*a(n-8) +9*a(n-9) +2*a(n-10) -3*a(n-11) +a(n-12). EXAMPLE Some solutions for n=3 ..1..1..1....1..1..0....1..1..0....0..3..1....0..2..0....1..2..1....0..1..1 ..0..3..0....0..3..1....1..3..0....1..1..0....1..2..1....0..2..0....1..3..0 CROSSREFS Row 2 of A221817. Sequence in context: A013030 A124962 A292088 * A331648 A009568 A139155 Adjacent sequences: A221815 A221816 A221817 * A221819 A221820 A221821 KEYWORD nonn AUTHOR R. H. Hardin, Jan 26 2013 STATUS approved

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Last modified June 3 18:44 EDT 2023. Contains 363116 sequences. (Running on oeis4.)