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 A252721 Number of (2+2) X (n+2) 0..3 arrays with every consecutive three elements in every row and diagonal having exactly two distinct values, and in every column and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order. 1
 45, 46, 50, 63, 69, 91, 107, 131, 163, 207, 243, 319, 395, 479, 619, 783, 939, 1231, 1547, 1871, 2443, 3087, 3723, 4879, 6155, 7439, 9739, 12303, 14859, 19471, 24587, 29711, 38923, 49167, 59403, 77839, 98315, 118799, 155659, 196623, 237579, 311311, 393227 (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) = a(n-2) + 2*a(n-3) - 2*a(n-5) for n>8. Empirical g.f.: x*(45 + 46*x + 5*x^2 - 73*x^3 - 73*x^4 + 18*x^5 + 4*x^6 + 2*x^7) / ((1 - x)*(1 + x)*(1 - 2*x^3)). - Colin Barker, Dec 05 2018 EXAMPLE Some solutions for n=4: ..0..1..0..0..2..0....0..0..1..0..0..2....0..1..1..0..1..1....0..0..1..1..2..2 ..0..0..1..0..0..2....1..3..3..0..3..3....0..2..0..0..2..0....1..2..2..3..3..0 ..0..3..3..0..3..3....2..2..0..0..1..0....0..0..2..0..0..2....3..3..0..0..1..1 ..0..1..0..0..1..0....0..0..1..0..0..1....0..3..3..0..3..3....0..1..1..2..2..3 CROSSREFS Row 2 of A252719. Sequence in context: A199523 A119415 A165866 * A042011 A031064 A183983 Adjacent sequences: A252718 A252719 A252720 * A252722 A252723 A252724 KEYWORD nonn AUTHOR R. H. Hardin, Dec 20 2014 STATUS approved

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Last modified March 27 22:47 EDT 2023. Contains 361575 sequences. (Running on oeis4.)