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A209625
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G.f. A(x) satisfies A(A(x)-2*A(x)^2)=x/(1-2*x)
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0
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1, 2, 6, 24, 114, 600, 3372, 19824, 120422, 749848, 4760228, 30688560, 200338740, 1321408656, 8791205496, 58912586784, 397228820742, 2692522813848, 18333530047428, 125325068538672, 859639878194844
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n)=T(n,1), T(n,m)=1/2*(binomial(n-1,m-1)*2^(n-m)-(sum(k=m+1..n-1, T(k,m)*sum(i=k..n, T(n,i)*binomial(k,i-k)*(-2)^(i-k)))+sum(i=m+1,n, T(n,i)*binomial(m,i-m)*(-2)^(i-m)))), T(n,n)=1.
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PROG
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(Maxima)
T(n, m):=if n=m then 1 else 1/2*(binomial(n-1, m-1)*2^(n-m)-(sum(T(k, m)*sum(T(n, i)*binomial(k, i-k)*(-2)^(i-k), i, k, n), k, m+1, n-1)+sum(T(n, i)*binomial(m, i-m)*(-2)^(i-m), i, m+1, n)));
makelist(T(n, 1), n, 1, 7);
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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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