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A140961
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Number of 3 X n {0,1}-matrices such that: (a) first and second row have a common 1, (b) second and third row have a common 1.
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0
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1, 17, 205, 2129, 20341, 184457, 1615405, 13808609, 116015461, 962575097, 7913168605, 64610052689, 524855128981, 4247421698537, 34274519697805, 275985344786369, 2218709434248901, 17815093293410777, 142915542082163005, 1145704555158361649, 9179974972732223221
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..21.
Andy Fugard, Counting first-order models (with n individuals) of syllogisms.
Index entries for linear recurrences with constant coefficients, signature (19,-118,240).
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FORMULA
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a(n) = 8^n-2*6^n+5^n.
G.f.: x*(2*x-1)/((5*x-1)*(6*x-1)*(8*x-1)). [Colin Barker, Nov 05 2012]
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CROSSREFS
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Cf. A051588.
Sequence in context: A279448 A017897 A016311 * A016306 A021092 A219124
Adjacent sequences: A140958 A140959 A140960 * A140962 A140963 A140964
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KEYWORD
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easy,nonn
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AUTHOR
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Andy Fugard, Vladeta Jovovic, Jul 26 2008
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STATUS
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approved
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