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 A251286 Number of (n+1) X (2+1) 0..1 arrays with every 2 X 2 subblock having a single 1 or two 1s on the same edge or main diagonally. 1
 22, 71, 219, 701, 2193, 6980, 21966, 69681, 219860, 696284, 2199557, 6960357, 21999804, 69591126, 220014756, 695843558, 2200194145, 6958021138, 22001843859, 69577286765, 220014836192, 695749296057, 2200100105526, 6957283657381 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 2*a(n-1) + 7*a(n-2) - 9*a(n-3) - 7*a(n-4) + 7*a(n-5) for n>6. Empirical g.f.: x*(22 + 27*x - 77*x^2 - 36*x^3 + 51*x^4 + x^5) / (1 - 2*x - 7*x^2 + 9*x^3 + 7*x^4 - 7*x^5). - Colin Barker, Nov 28 2018 EXAMPLE Some solutions for n=4: ..0..1..1....1..1..0....1..1..1....0..0..1....0..0..0....1..1..1....1..1..1 ..0..0..0....0..0..0....0..0..0....1..0..0....0..1..0....0..0..0....0..0..0 ..1..0..1....0..1..0....1..1..0....0..1..0....0..0..1....1..1..0....0..1..1 ..1..0..1....0..0..0....0..0..0....0..0..1....1..0..0....0..0..1....0..0..0 ..1..0..0....0..1..1....0..1..0....1..0..0....0..1..1....1..0..0....1..1..1 CROSSREFS Column 2 of A251292. Sequence in context: A334034 A044160 A044541 * A080861 A241521 A143838 Adjacent sequences:  A251283 A251284 A251285 * A251287 A251288 A251289 KEYWORD nonn AUTHOR R. H. Hardin, Dec 01 2014 STATUS approved

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Last modified May 25 19:19 EDT 2022. Contains 354071 sequences. (Running on oeis4.)