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 A202796 Number of n X 2 binary arrays with every one adjacent to another one horizontally or vertically. 4
 2, 10, 36, 126, 454, 1632, 5854, 21010, 75412, 270662, 971438, 3486624, 12513958, 44914250, 161203204, 578579694, 2076599286, 7453190368, 26750489166, 96011055010, 344596415668, 1236802258678, 4439047411742, 15932330156576 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 2 of A202802. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 3*a(n-1) + a(n-2) + 4*a(n-3). Empirical g.f.: 2*x*(1 + 2*x + 2*x^2) / (1 - 3*x - x^2 - 4*x^3). - Colin Barker, Feb 20 2018 EXAMPLE Some solutions for n=5: ..0..1....0..0....0..1....1..0....0..0....1..0....1..1....0..1....0..1....1..0 ..0..1....1..0....1..1....1..0....0..0....1..0....1..1....1..1....1..1....1..1 ..1..1....1..1....1..1....1..1....0..1....0..0....1..0....0..0....1..0....0..1 ..1..1....0..1....1..0....1..0....0..1....0..1....0..1....1..0....0..0....1..0 ..1..0....1..1....1..0....1..0....0..0....0..1....1..1....1..1....0..0....1..0 CROSSREFS Cf. A202802. Sequence in context: A266942 A265844 A192858 * A001582 A026546 A256105 Adjacent sequences:  A202793 A202794 A202795 * A202797 A202798 A202799 KEYWORD nonn AUTHOR R. H. Hardin, Dec 24 2011 STATUS approved

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Last modified February 20 06:26 EST 2019. Contains 320332 sequences. (Running on oeis4.)