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 A195249 Number of lower triangles of a 3 X 3 0..n array with each element differing from all of its diagonal, vertical, antidiagonal and horizontal neighbors by two or less. 1
 64, 729, 1682, 2729, 3776, 4823, 5870, 6917, 7964, 9011, 10058, 11105, 12152, 13199, 14246, 15293, 16340, 17387, 18434, 19481, 20528, 21575, 22622, 23669, 24716, 25763, 26810, 27857, 28904, 29951, 30998, 32045, 33092, 34139, 35186, 36233, 37280, 38327 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 3 of A195248. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n) = 1047*n - 1459 for n>2. Conjectures from Colin Barker, May 06 2018: (Start) G.f.: x*(64 + 601*x + 288*x^2 + 94*x^3) / (1 - x)^2. a(n) = 2*a(n-1) - a(n-2) for n>4. (End) EXAMPLE Some solutions for n=5: ..2......1......0......0......4......5......1......1......5......3 ..3.4....2.3....2.0....0.2....5.4....3.5....1.3....2.3....3.3....2.2 ..4.4.4..2.1.2..1.1.1..1.1.3..4.4.5..5.5.3..2.1.3..4.3.4..2.3.3..0.0.2 CROSSREFS Cf. A195248. Sequence in context: A354178 A367803 A161860 * A223953 A224137 A016899 Adjacent sequences: A195246 A195247 A195248 * A195250 A195251 A195252 KEYWORD nonn AUTHOR R. H. Hardin, Sep 13 2011 STATUS approved

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Last modified August 6 17:01 EDT 2024. Contains 374980 sequences. (Running on oeis4.)