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A172391
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G.f. satisfies: A(x) = G(x/A(x))^2 and G(x)^2 = A(x*G(x)^2) where G(x) = Sum_{n>=0} C(2n,n)*C(2n+2,n+1)/(n+2)*x^n is the g.f. of A172392.
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2
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1, 8, 12, 0, 28, 0, 264, 0, 3720, 0, 63840, 0, 1232432, 0, 25731216, 0, 568130552, 0, 13081215840, 0, 311178567648, 0, 7597974517056, 0, 189518147463232, 0, 4811962763222784, 0, 124028853694440640, 0, 3238304402221646880, 0
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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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G.f.: A(x) = x/Series_Reversion(x*G(x)^2)) where G(x) is the g.f. of A172392(n) = A000108(n+1)*A000984(n).
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EXAMPLE
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G.f.: A(x) = 1 + 8*x + 12*x^2 + 28*x^4 + 264*x^6 + 3720*x^8 +...
where A(x) = G(x/A(x))^2 where G(x) is the g.f. of A172392:
G(x) = 1 + 4*x + 30*x^2 + 280*x^3 + 2940*x^4 + 33264*x^5 +...+ A172392(n)*x^n +...
G(x) = 1 + 2*2*x + 5*6*x^2 + 14*20*x^3 + 42*70*x^4 + 132*252*x^5 +...
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PROG
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(PARI) {a(n)=local(G=sum(m=0, n, binomial(2*m, m)*binomial(2*m+2, m+1)/(m+2)*x^m)+x*O(x^n)); polcoeff(x/serreverse(x*G^2), n)}
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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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