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 A184368 1/3 the number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock having at least two equal elements connected horizontally or vertically. 2
 21, 153, 1107, 8019, 58077, 420633, 3046491, 22064643, 159806277, 1157419449, 8382773187, 60713414163, 439725443661, 3184773389433, 23066169329547, 167059976482179, 1209955382858997, 8763272085493593, 63469230958692531 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 1 of A184376. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n) = 6*a(n-1) + 9*a(n-2). Conjectures from Colin Barker, Feb 27 2018: (Start) G.f.: 3*x*(7 + 9*x) / (1 - 6*x - 9*x^2). a(n) = ((3-3*sqrt(2))^n*(-4+3*sqrt(2)) + (3*(1+sqrt(2)))^n*(4+3*sqrt(2))) / (2*sqrt(2)). (End) EXAMPLE Some solutions for 3 X 2 with a(1,1)=0: ..0..0....0..0....0..1....0..0....0..0....0..1....0..1....0..2....0..1....0..0 ..1..0....2..2....1..1....2..1....0..2....0..0....2..1....0..2....0..1....1..2 ..2..0....1..1....2..0....0..0....0..2....0..2....2..2....0..2....0..2....1..0 CROSSREFS Cf. A184376. Sequence in context: A221694 A229262 A184376 * A078396 A301883 A302080 Adjacent sequences: A184365 A184366 A184367 * A184369 A184370 A184371 KEYWORD nonn AUTHOR R. H. Hardin, Jan 12 2011 STATUS approved

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Last modified November 30 09:21 EST 2022. Contains 358438 sequences. (Running on oeis4.)