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A367073
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G.f. satisfies A(x) = 1 + 2*x + x^3*A(x)^3.
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3
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1, 2, 0, 1, 6, 12, 11, 30, 120, 252, 408, 1104, 3415, 7710, 15984, 42609, 118422, 281820, 657468, 1732008, 4608288, 11375240, 28100400, 73598112, 192776895, 487507038, 1239516384, 3241480275, 8460205842, 21733941060, 56121723411, 146904032622, 383900676120
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = Sum_{k=0..floor(n/3)} 2^(n-3*k) * binomial(2*k+1,n-3*k) * A001764(k).
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PROG
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(PARI) a(n) = sum(k=0, n\3, 2^(n-3*k)*binomial(2*k+1, n-3*k)*binomial(3*k, k)/(2*k+1));
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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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