A141203 G.f. satisfies: A(x - x*B(x)) = x where B(x) = (A(x) - A(-x))/2, the odd bisection of A(x).

1, 1, 2, 7, 26, 124, 596, 3365, 18954, 120242, 760140, 5281436, 36617556, 274624708, 2059397032, 16520347463, 132773992954, 1132184343204, 9689336590700, 87424470404886, 792807348829740, 7541745922428356, 72187384283011000

Offset

1,3

Comments

a(n) == 1 (mod 2) iff n = 2^k for k>=0.

Links

Paul D. Hanna, Table of n, a(n) for n = 1..300

Example

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.

Prog

(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)}

Crossrefs

Sequence in context: A302691 A081566 A213094 * A346749 A096803 A036757

Adjacent sequences: A141200 A141201 A141202 * A141204 A141205 A141206

Keyword

nonn

Author

Paul D. Hanna, Jun 13 2008

Status

approved