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A052886
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A simple grammar.
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5
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0, 1, 3, 19, 207, 3211, 64383, 1581259, 45948927, 1541641771, 58645296063, 2494091717899, 117258952478847, 6038838138717931, 338082244882740543, 20443414320405268939, 1327850160592214291967, 92200405122521276427691
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 859
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FORMULA
| E.g.f.: 1/2-1/2*(5-4*exp(x))^(1/2)
a(n) = 1+Sum_{k=1..n-1} binomial(n, k)*a(k)*a(n-k). - Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 02 2005
a(n)=sum(k!*stirling2(n,k)*C(k-1),k,1,n), C(k) - Catalan numbers (A000108). [From Kruchinin Vladimir (kru(AT)ie.tusur.ru), Sep 15 2010]
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MAPLE
| spec := [S, {C=Set(Z, 1 <= card), S=Prod(B, C), B=Sequence(S)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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PROG
| (Pari) N=66; x='x+O('x^N); /* that many terms */
Vec(serlaplace(serreverse(log(1+x-x^2)))) /* show terms */ /* Joerg Arndt, May 25 2011 */
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CROSSREFS
| Sequence in context: A201827 A108993 A182956 * A180563 A079144 A049056
Adjacent sequences: A052883 A052884 A052885 * A052887 A052888 A052889
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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