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A022015
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a(n)=2a(n-1)+3a(n-2)+2a(n-3)+3a(n-4).
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1
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2, 6, 19, 61, 197, 633, 2036, 6548, 21061, 67737, 217861, 700699, 2253638, 7248306, 23312507, 74979305, 241153657, 775615161, 2494587424, 8023265560, 25804984685, 82995786381, 266936820209, 858540765611
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OFFSET
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0,1
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LINKS
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FORMULA
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G.f.: -(((1+x)*(2+x^2))/(-1+x(2+3*x)*(1+x^2))). - Harvey P. Dale, May 04 2015
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MATHEMATICA
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LinearRecurrence[{2, 3, 2, 3}, {2, 6, 19, 61}, 30] (* Harvey P. Dale, May 04 2015 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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