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 A195000 Number of lower triangles of a 4 X 4 0..n array with each element differing from all of its horizontal and vertical neighbors by one. 1
 2, 80, 248, 458, 672, 888, 1104, 1320, 1536, 1752, 1968, 2184, 2400, 2616, 2832, 3048, 3264, 3480, 3696, 3912, 4128, 4344, 4560, 4776, 4992, 5208, 5424, 5640, 5856, 6072, 6288, 6504, 6720, 6936, 7152, 7368, 7584, 7800, 8016, 8232, 8448, 8664, 8880, 9096 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 4 of A194998. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Conjectures from Colin Barker, May 06 2018: (Start) G.f.: 2*x*(1 + 38*x + 45*x^2 + 21*x^3 + 2*x^4 + x^5) / (1 - x)^2. a(n) = 24*(9*n - 17) for n>4. a(n) = 2*a(n-1) - a(n-2) for n>6. (End) EXAMPLE Some solutions for n=4: ..1........4........3........4........2........1........1........0 ..2.1......3.2......2.3......3.2......3.4......0.1......2.1......1.2 ..1.0.1....2.1.2....3.4.3....2.1.2....2.3.4....1.2.1....3.2.3....2.3.2 ..0.1.0.1..1.2.3.4..2.3.2.1..1.0.1.0..3.4.3.2..2.1.2.1..2.3.2.3..3.2.1.0 CROSSREFS Cf. A194998. Sequence in context: A100421 A319438 A371151 * A073499 A222826 A123828 Adjacent sequences: A194997 A194998 A194999 * A195001 A195002 A195003 KEYWORD nonn AUTHOR R. H. Hardin, Sep 07 2011 STATUS approved

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Last modified September 12 01:49 EDT 2024. Contains 375842 sequences. (Running on oeis4.)