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A124495 G.f.: A(x) = 1/[1-x - Sum_{n>=1} A001147(n)*x^(2n) ] where A001147(n) = (2n)!/(n!*2^n) is the double factorials. 0
1, 1, 2, 3, 8, 14, 43, 81, 283, 556, 2243, 4512, 21374, 43469, 243817, 497217, 3289606, 6697795, 51583952, 104698998, 922789643, 1867079621, 18522929815, 37380015420, 411572179999, 828925168492, 10014624164666, 20140445929353 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Is this sequence equal to A076876 (meandric numbers for a river crossing two parallel roads at n points)?

LINKS

Table of n, a(n) for n=0..27.

EXAMPLE

G.f.: A(x) = 1/(1-x - x^2 - 3*x^4 - 15*x^6 - 105*x^8 - 945*x^10 -...).

PROG

(PARI) a(n)=polcoeff(1/(1-x-sum(k=1, n\2, (2*k)!/k!/2^k*x^(2*k))+x*O(x^n)), n)

CROSSREFS

Cf. A001147.

Sequence in context: A107321 A005316 A076876 * A007919 A249167 A205101

Adjacent sequences:  A124492 A124493 A124494 * A124496 A124497 A124498

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Nov 04 2006

STATUS

approved

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Last modified October 19 16:41 EDT 2018. Contains 316367 sequences. (Running on oeis4.)