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A365697
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G.f. satisfies A(x) = 1 + x^4*A(x)^3 / (1 - x*A(x)).
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2
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1, 0, 0, 0, 1, 1, 1, 1, 4, 8, 13, 19, 38, 79, 153, 273, 509, 999, 1979, 3818, 7331, 14279, 28189, 55599, 109275, 215165, 426093, 846638, 1683215, 3348212, 6673679, 13333171, 26679522, 53437369, 107151335, 215154204, 432586412, 870678377, 1754094266
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OFFSET
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0,9
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LINKS
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FORMULA
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a(n) = Sum_{k=0..floor(n/4)} binomial(n-3*k-1,n-4*k) * binomial(n-k+1,k) / (n-k+1).
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PROG
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(PARI) a(n) = sum(k=0, n\4, binomial(n-3*k-1, n-4*k)*binomial(n-k+1, k)/(n-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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