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 A204708 Number of (n+1) X 4 0..1 arrays with the permanents of all 2 X 2 subblocks equal and nonzero. 1
 25, 81, 257, 833, 2689, 8705, 28161, 91137, 294913, 954369, 3088385, 9994241, 32342017, 104660993, 338690049, 1096024065, 3546808321, 11477712897, 37142659073, 120196169729, 388962975745, 1258710630401, 4073273163777 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 3 of A204713. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 3*a(n-1) +2*a(n-2) -4*a(n-3). Conjectures from Colin Barker, Jun 09 2018: (Start) G.f.: x*(25 + 6*x - 36*x^2) / ((1 - x)*(1 - 2*x - 4*x^2)). a(n) = (5 + (20-8*sqrt(5))*(1-sqrt(5))^n + 4*(1+sqrt(5))^n*(5+2*sqrt(5))) / 5. (End) EXAMPLE Some solutions for n=4: ..1..1..1..0....0..1..1..1....1..0..1..0....1..1..0..1....0..1..0..1 ..1..0..1..1....1..1..0..1....1..1..0..1....1..0..1..1....1..1..1..0 ..1..1..0..1....1..0..1..1....1..0..1..0....0..1..1..0....1..0..1..1 ..0..1..1..0....0..1..1..0....1..1..1..1....1..1..0..1....0..1..1..0 ..1..0..1..1....1..0..1..1....0..1..0..1....1..0..1..1....1..1..0..1 CROSSREFS Cf. A204713. Sequence in context: A223181 A016814 A280343 * A174623 A100487 A157530 Adjacent sequences:  A204705 A204706 A204707 * A204709 A204710 A204711 KEYWORD nonn AUTHOR R. H. Hardin, Jan 18 2012 STATUS approved

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Last modified September 20 19:47 EDT 2021. Contains 347589 sequences. (Running on oeis4.)