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A192441
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Coefficient of x^(2*n) in the expansion of (1 + x^3 + x^4)^n.
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2
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1, 0, 2, 3, 6, 30, 35, 210, 350, 1344, 3402, 9240, 29139, 72072, 231660, 603603, 1814670, 5095376, 14507324, 42401502, 118974466, 349305120, 990073812, 2877816304, 8272748675, 23852438880, 69116072950, 198980348385, 577566713520, 1667118322590, 4834810467135
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OFFSET
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0,3
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..200
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FORMULA
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a(n) = Sum_{k=ceiling(n/2)..floor(2*n/3)} binomial(n,k)*binomial(k,2*n-3*k). - R. J. Mathar, Jul 01 2011
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PROG
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(PARI) a(n)=polcoeff((1+x^3+x^4)^n, 2*n);
(Maxima) makelist((coeff(expand((1+x^3+x^4)^n), x, 2*n)), n, 0, 30); /* Bruno Berselli, Jul 01 2011 */
(Magma) P<x>:=PolynomialRing(Integers()); [ Coefficients((1+x^3+x^4)^n)[ 2*n+1 ]: n in [0..30] ]; // Bruno Berselli, Jul 01 2011
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CROSSREFS
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Cf. A002426, A192440.
Sequence in context: A277809 A051717 A330030 * A108326 A002234 A074005
Adjacent sequences: A192438 A192439 A192440 * A192442 A192443 A192444
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KEYWORD
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nonn
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AUTHOR
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Joerg Arndt, Jul 01 2011
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STATUS
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approved
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