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A081126
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Binomial transform of n!/floor(n/2)!.
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1
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1, 2, 5, 16, 53, 206, 817, 3620, 16361, 80218, 401501, 2139512, 11641885, 66599846, 388962953, 2367284236, 14700573137, 94523836850, 619674301621, 4186249123808, 28809504493061, 203556335785342, 1463877667140065
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Row sums of exponential Riordan array [(1+x),x(1+x)]. - Paul Barry (pbarry(AT)wit.ie), Apr 17 2007
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LINKS
| Guo-Niu Han, Enumeration of Standard Puzzles
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FORMULA
| a(n) =Sum {k=0..n, C(n, k)*n!/floor(n/2)!}
a(n) = A018191(n+1).
E.g.f.: (1+x)*exp(x+x^2). - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 06 2006
a(n)=Sum{k=0..n, C(n,k)*k!/floor(k/2)!}; a(n)=sum{k=0..n, C(k+1,n-k)*n!/k!}. - Paul Barry (pbarry(AT)wit.ie), Apr 17 2007
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CROSSREFS
| Cf. A018191, A081125.
Sequence in context: A148397 A148398 A100442 * A018191 A006191 A149959
Adjacent sequences: A081123 A081124 A081125 * A081127 A081128 A081129
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Mar 07 2003, Apr 17 2007
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