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A063651
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Number of ways to tile a 7 X n rectangle with 1 X 1 and 2 X 2 tiles.
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3
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1, 1, 21, 85, 747, 4375, 31387, 202841, 1382259, 9167119, 61643709, 411595537, 2758179839, 18448963469, 123518353059, 826573277157, 5532716266089, 37028886137273, 247839719105625, 1658772577825883, 11102227136885119
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = 3a(n-1) + 30a(n-2) - 17a(n-3) - 138a(n-4) + 85a(n-5) + 116a(n-6) - 42a(n-7) - 32a(n-8). - Keith Schneider (kschneid(AT)bulldog.unca.edu), Apr 02 2006
G.f.: ( 1 -2*x -12*x^2 +9*x^3 +17*x^4 -6*x^5 -6*x^6 ) / ( 1 -3*x -30*x^2 +17*x^3 +138*x^4 -85*x^5 -116*x^6 +42*x^7 +32*x^8 ). - Colin Barker, Nov 29 2012
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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