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A141203
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G.f. satisfies: A(x - x*B(x)) = x where B(x) = (A(x) - A(-x))/2, the odd bisection of A(x).
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1
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1, 1, 2, 7, 26, 124, 596, 3365, 18954, 120242, 760140, 5281436, 36617556, 274624708, 2059397032, 16520347463, 132773992954, 1132184343204, 9689336590700, 87424470404886, 792807348829740, 7541745922428356, 72187384283011000
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OFFSET
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1,3
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COMMENTS
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a(n) == 1 (mod 2) iff n = 2^k for k>=0.
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LINKS
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Paul D. Hanna, Table of n, a(n) for n = 1..300
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EXAMPLE
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G.f.: A(x) = x + x^2 + 2*x^3 + 7*x^4 + 26*x^5 + 124*x^6 + 596*x^7 +...
The series reversion of A(x) = x - x*[A(x) - A(-x)]/2, thus:
A(x - x^2 - 2*x^4 - 26*x^6 - 596*x^8 - 18954*x^10 -...) = x.
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PROG
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(PARI) {a(n)=local(A=x+x^2); for(i=0, n, A=serreverse(x-x/2*(A-subst(A, x, -x+x*O(x^n))))) ; polcoeff(A, n)}
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CROSSREFS
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Sequence in context: A302691 A081566 A213094 * A346749 A096803 A036757
Adjacent sequences: A141200 A141201 A141202 * A141204 A141205 A141206
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna, Jun 13 2008
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STATUS
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approved
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