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A211911
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Number of lower triangular nXn arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal, vertical, diagonal or antidiagonal neighbor, and containing the value n(n+1)/2-2
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1
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0, 1, 6, 25, 70, 156, 301, 526, 855, 1315, 1936, 2751, 3796, 5110, 6735, 8716, 11101, 13941, 17290, 21205, 25746, 30976, 36961, 43770, 51475, 60151, 69876, 80731, 92800, 106170, 120931, 137176, 155001, 174505, 195790, 218961, 244126, 271396, 300885
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OFFSET
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1,3
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COMMENTS
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Column 1 of A211916
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..74
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FORMULA
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Empirical: a(n) = (1/8)*n^4 + (1/4)*n^3 - (17/8)*n^2 + (11/4)*n for n>1
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EXAMPLE
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Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.2......1.2......1.2......1.2
..3.4.5....3.4.5....3.4.5....3.4.5....3.4.5....3.4.5....3.4.1....3.4.5
..0.6.7.8..6.7.8.1..1.6.7.8..6.7.3.8..6.7.8.7..6.1.7.8..5.6.7.8..6.7.8.3
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CROSSREFS
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Sequence in context: A001664 A096958 A166814 * A133714 A164271 A220275
Adjacent sequences: A211908 A211909 A211910 * A211912 A211913 A211914
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin Apr 25 2012
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STATUS
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approved
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