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 A185405 1/7 the number of n X 2 0..6 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors. 1
 1, 13, 150, 1848, 22656, 278832, 3430776, 42221928, 519611520, 6394769688, 78699293256, 968538893952, 11919644165496, 146693048343528, 1805326578739200, 22217849450044248, 273431322619829256 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 2 of A185409. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n) = 11*a(n-1) + 23*a(n-2) - 72*a(n-3) - 144*a(n-4) - 216*a(n-5). Empirical g.f.: x*(1 + 2*x - 16*x^2 - 29*x^3 - 42*x^4) / (1 - 11*x - 23*x^2 + 72*x^3 + 144*x^4 + 216*x^5). - Colin Barker, Apr 15 2018 EXAMPLE Some solutions for 3 X 2 with a(1,1)=0: ..0..0....0..0....0..0....0..0....0..0....0..2....0..3....0..0....0..0....0..0 ..2..5....2..2....5..1....6..6....2..2....0..2....0..3....0..6....0..1....6..5 ..2..5....5..5....5..1....5..5....4..4....3..3....3..3....6..6....0..1....6..5 CROSSREFS Cf. A185409. Sequence in context: A163148 A355414 A345217 * A051475 A242576 A173448 Adjacent sequences: A185402 A185403 A185404 * A185406 A185407 A185408 KEYWORD nonn AUTHOR R. H. Hardin, Jan 26 2011 STATUS approved

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Last modified September 30 21:59 EDT 2023. Contains 365812 sequences. (Running on oeis4.)