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 A281058 Number of 3 X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards. 1
 0, 6, 68, 239, 618, 1403, 2828, 5482, 10342, 19136, 34907, 62976, 112617, 199929, 352771, 619208, 1081946, 1882951, 3265367, 5644772, 9730124, 16728760, 28693405, 49108842, 83882613, 143016171, 243420929, 413658928, 701916100, 1189400585 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 5*a(n-1) - 7*a(n-2) - 2*a(n-3) + 10*a(n-4) - 2*a(n-5) - 5*a(n-6) + a(n-7) + a(n-8) for n>15. Empirical g.f.: x^2*(6 + 38*x - 59*x^2 - 89*x^3 + 62*x^4 - 51*x^5 + 175*x^6 + 166*x^7 - 217*x^8 - 106*x^9 + 71*x^10 + 21*x^11 - 7*x^12 - x^13) / ((1 - x)^2*(1 - x - x^2)^3). - Colin Barker, Feb 15 2019 EXAMPLE Some solutions for n=4: ..0..1..0..0. .0..1..0..0. .0..1..1..0. .0..0..0..0. .0..0..1..1 ..0..1..0..1. .0..1..0..0. .1..0..1..1. .1..0..1..0. .1..0..1..0 ..0..1..1..0. .0..1..1..0. .1..0..1..0. .1..0..1..1. .1..0..0..1 CROSSREFS Row 3 of A281056. Sequence in context: A054746 A116005 A297435 * A152390 A200059 A183470 Adjacent sequences:  A281055 A281056 A281057 * A281059 A281060 A281061 KEYWORD nonn AUTHOR R. H. Hardin, Jan 13 2017 STATUS approved

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Last modified December 3 05:05 EST 2021. Contains 349445 sequences. (Running on oeis4.)