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A026385
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Sum{T(n-k,k)}, 0<=k<=[ n/2 ], where T is the array in A026374.
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3
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1, 1, 2, 4, 6, 11, 20, 33, 59, 104, 178, 314, 549, 952, 1669, 2913, 5074, 8872, 15482, 27007, 47172, 82325, 143675, 250848, 437822, 764198, 1334041, 2328512, 4064457, 7094833, 12384034, 21616716, 37732990, 65863651
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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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G.f.: (1+x+x^2)/(1-x^2-3x^3-x^4). - Ralf Stephan, Apr 30 2004
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MATHEMATICA
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LinearRecurrence[{0, 1, 3, 1}, {1, 1, 2, 4}, 40] (* Harvey P. Dale, Jun 18 2014 *)
CoefficientList[Series[(1 + x + x^2)/(1 - x^2 - 3 x^3 - x^4), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 19 2014 *)
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PROG
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(Magma) I:=[1, 1, 2, 4]; [n le 4 select I[n] else Self(n-2)+3*Self(n-3)+Self(n-4): n in [1..40]]; // Vincenzo Librandi, Jun 19 2014
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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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