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A112808
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Expansion of solution of functional equation.
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0
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1, 1, 2, 5, 14, 43, 142, 495, 1794, 6683, 25388, 97852, 381406, 1500317, 5947798, 23739795, 95326150, 384845581, 1561220986, 6361205709, 26021379044, 106826116871, 439987835410, 1817594141822, 7529012424286, 31265738342993
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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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Given g.f. A(x), then series reversion of B(x)=x*A(x^3) is -B(-x).
Given g.f. A(x), then y=x*A(x^3) satisfies y=x+(xy)^2/(1-(xy)^6).
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PROG
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(PARI) {a(n)=local(A); if(n<0, 0, A=x+O(x^4); for(k=1, n, A=x+subst(x^2/(1-x^6), x, x*A)); polcoeff(A, 3*n+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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