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Search: id:A124495
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| A124495 |
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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. |
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+0
1
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| 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; listen)
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OFFSET
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0,3
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COMMENT
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Is this sequence equal to A076876 (meandric numbers for a river crossing two parallel roads at n points)?
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EXAMPLE
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G.f.: A(x) = 1/(1-x - x^2 - 3*x^4 - 15*x^6 - 105*x^8 - 945*x^10 -...).
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PROGRAM
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(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)
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CROSSREFS
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Cf. A001147.
Sequence in context: A107321 A005316 A076876 this_sequence A007919 A069752 A004731
Adjacent sequences: A124492 A124493 A124494 this_sequence A124496 A124497 A124498
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Nov 04 2006
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