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 A251276 Number of (n+1) X (1+1) 0..3 arrays with no 2 X 2 subblock having its maximum diagonal element less than its minimum antidiagonal element. 1
 230, 3264, 46244, 655040, 9278296, 131421696, 1861511440, 26367218944, 373476205664, 5290071598080, 74930764222016, 1061350366002176, 15033405986262400, 212939386264141824, 3016161624583446784 (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) = 16*a(n-1) - 26*a(n-2). Conjectures from Colin Barker, Nov 27 2018: (Start) G.f.: 2*x*(115 - 208*x) / (1 - 16*x + 26*x^2). a(n) = ((8-sqrt(38))^n*(-51+8*sqrt(38)) + (8+sqrt(38))^n*(51+8*sqrt(38))) / sqrt(38). (End) EXAMPLE Some solutions for n=3: ..0..0....3..2....2..0....3..2....0..2....1..0....1..3....2..3....3..3....0..0 ..3..0....2..0....2..1....2..2....1..1....3..2....1..0....0..0....1..3....1..0 ..0..0....3..0....3..0....2..0....1..2....1..1....2..3....2..3....1..3....2..0 ..1..2....2..2....1..3....3..2....2..2....1..2....1..0....0..0....2..2....2..1 CROSSREFS Column 1 of A251283. Sequence in context: A211716 A251445 A251283 * A194490 A232379 A333136 Adjacent sequences:  A251273 A251274 A251275 * A251277 A251278 A251279 KEYWORD nonn AUTHOR R. H. Hardin, Dec 01 2014 STATUS approved

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Last modified April 22 14:20 EDT 2021. Contains 343177 sequences. (Running on oeis4.)