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A052750
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a(n) = (2*n+1)^(n-1). E.g.f.: exp(-1/2*W(-2*x)), where W is Lambert's W function.
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5
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1, 1, 5, 49, 729, 14641, 371293, 11390625, 410338673, 16983563041, 794280046581, 41426511213649, 2384185791015625, 150094635296999121, 10260628712958602189, 756943935220796320321, 59938945498865420543457
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| a(n+1) is the number of labeled incomplete ternary trees on n vertices in which each left child has a larger label than its parent. - Brian Drake (bdrake(AT)brandeis.edu), Jul 28 2008
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 706
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MAPLE
| spec := [S, {B=Prod(Z, S, S), S=Set(B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
with(finance):seq(mul(cashflows([n, n, 1], 0), k=2..n), n=0..20); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 22 2008]
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PROG
| (PARI) a(n)=(2*n+1)^(n-1) \\ Charles R Greathouse IV, Nov 20 2011
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CROSSREFS
| Sequence in context: A102773 A028575 A006554 * A145088 A192557 A062995
Adjacent sequences: A052747 A052748 A052749 * A052751 A052752 A052753
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
| Better description from Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 02 2003
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