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 A259216 Number of (n+1) X (2+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0011 or 0101. 2
 13, 23, 40, 71, 127, 230, 421, 779, 1456, 2747, 5227, 10022, 19345, 37559, 73288, 143615, 282439, 557126, 1101709, 2183123, 4333408, 8613683, 17141395, 34143686, 68062297, 135760415, 270931576, 540909719, 1080276751, 2158057382, 4312075957 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 Index entries for linear recurrences with constant coefficients, signature (3,-1,-2). FORMULA a(n) = 3*a(n-1) - a(n-2) - 2*a(n-3). From Colin Barker, Dec 24 2018: (Start) G.f.: x*(13 - 16*x - 16*x^2) / ((1 - 2*x)*(1 - x - x^2)). a(n) = 2^(1+n) + (3*2^(-n)*((1-sqrt(5))^n*(-2+sqrt(5)) + (1+sqrt(5))^n*(2+sqrt(5)))) / sqrt(5). (End) a(n) = 2^(n+1)+3*A000045(n+3). - R. J. Mathar, Oct 09 2020 EXAMPLE Some solutions for n=4: ..0..1..0....1..0..1....1..0..1....0..1..0....0..1..0....1..1..1....1..0..1 ..1..0..1....0..1..0....1..0..1....1..0..1....1..0..1....0..0..0....1..0..1 ..0..1..0....1..0..1....0..1..0....1..0..1....0..1..0....0..0..0....0..1..0 ..1..0..1....0..1..0....0..1..0....1..0..1....0..1..0....0..0..0....0..1..0 ..0..1..0....1..0..1....0..1..0....0..1..0....1..0..1....1..1..1....1..0..1 CROSSREFS Column 2 of A259222. Sequence in context: A164434 A164494 A164407 * A339867 A135283 A225519 Adjacent sequences: A259213 A259214 A259215 * A259217 A259218 A259219 KEYWORD nonn,easy AUTHOR R. H. Hardin, Jun 21 2015 STATUS approved

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Last modified December 7 14:37 EST 2023. Contains 367656 sequences. (Running on oeis4.)