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 A223395 4 X 4 square grid graph coloring a rectangular array: number of n X 1 0..15 arrays where 0..15 label nodes of the square grid graph and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. 1
 16, 48, 152, 488, 1576, 5096, 16488, 53352, 172648, 558696, 1807976, 5850728, 18933352, 61269608, 198272616, 641623656, 2076337768, 6719170152, 21743691368, 70364063336, 227702892136, 736862037608, 2384535643752, 7716519437928 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 1 of A223402. 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, Aug 20 2018: (Start) G.f.: 8*x*(2 - 3*x^2) / ((1 - x)*(1 - 2*x - 4*x^2)). a(n) = (8 + (11-5*sqrt(5))*(1-sqrt(5))^n + (1+sqrt(5))^n*(11+5*sqrt(5))) / 5. (End) EXAMPLE Some solutions for n=3: .12....9....5....0...10....2....5....0....7....1...10....6...12...11...15....2 ..8...13....6....1....9....3....6....4....3....0....9...10...13...10...11....1 .12...12....2....2....8....2....5....5....2....1...10...11....9...11...10....0 Vertex neighbors: 0 -> 1 4 1 -> 0 2 5 2 -> 1 3 6 3 -> 2 7 4 -> 0 5 8 5 -> 4 1 6 9 6 -> 5 2 7 10 7 -> 6 3 11 8 -> 4 9 12 9 -> 8 5 10 13 10 -> 9 6 11 14 11 -> 10 7 15 12 -> 8 13 13 -> 12 9 14 14 -> 13 10 15 15 -> 14 11 CROSSREFS Cf. A223402. Sequence in context: A211598 A235541 A109098 * A202329 A223599 A223692 Adjacent sequences: A223392 A223393 A223394 * A223396 A223397 A223398 KEYWORD nonn AUTHOR R. H. Hardin, Mar 19 2013 STATUS approved

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Last modified February 21 12:17 EST 2024. Contains 370235 sequences. (Running on oeis4.)