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 A252726 Number of (7+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
 257, 220, 224, 257, 288, 324, 373, 452, 512, 617, 768, 900, 1093, 1412, 1664, 2057, 2688, 3204, 3973, 5252, 6272, 7817, 10368, 12420, 15493, 20612, 24704, 30857, 41088, 49284, 61573, 82052, 98432, 123017, 163968, 196740, 245893, 327812, 393344 (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-1) + 3*a(n-3) + 3*a(n-4) - 2*a(n-6) - 2*a(n-7) for n>9. Empirical g.f.: x*(257 + 477*x + 444*x^2 - 290*x^3 - 886*x^4 - 720*x^5 - 232*x^6 + 144*x^7 + 16*x^8) / ((1 - x)*(1 + x)*(1 + x + x^2)*(1 - 2*x^3)). - Colin Barker, Dec 06 2018 EXAMPLE Some solutions for n=4: ..0..1..1..0..1..1....0..1..1..0..1..1....0..1..0..0..1..0....0..0..1..0..0..2 ..0..2..0..0..3..0....1..0..1..1..0..1....1..1..2..1..1..2....0..3..3..0..3..3 ..0..0..2..0..0..3....2..2..1..2..2..1....3..1..1..2..1..1....0..1..0..0..1..0 ..0..1..1..0..1..1....0..1..1..0..1..1....0..1..0..0..1..0....0..0..1..0..0..1 ..0..3..0..0..2..0....1..0..1..1..0..1....1..1..3..1..1..2....0..3..3..0..3..3 ..0..0..3..0..0..2....2..2..1..2..2..1....3..1..1..3..1..1....0..2..0..0..1..0 ..0..1..1..0..1..1....3..1..1..0..1..1....0..1..0..0..1..0....0..0..2..0..0..1 ..0..3..0..0..3..0....1..3..1..1..0..1....1..1..3..1..1..3....0..3..3..0..3..3 ..0..0..3..0..0..3....2..2..1..2..2..1....2..1..1..3..1..1....0..2..0..0..2..0 CROSSREFS Row 7 of A252719. Sequence in context: A273775 A182912 A276233 * A260679 A043676 A296901 Adjacent sequences:  A252723 A252724 A252725 * A252727 A252728 A252729 KEYWORD nonn AUTHOR R. H. Hardin, Dec 20 2014 STATUS approved

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Last modified May 20 20:15 EDT 2022. Contains 353876 sequences. (Running on oeis4.)