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A101490
G.f. satisfies A(x) = x*(1+A^2)^2/(1-A+A^2).
3
0, 1, 1, 3, 8, 25, 80, 267, 911, 3170, 11192, 39993, 144320, 525124, 1924196, 7093603, 26288928, 97878831, 365918064, 1372982706, 5168555770, 19514482964, 73876936272, 280363191353, 1066357904128, 4064204607372
OFFSET
0,4
LINKS
M. Bousquet-Mélou, Limit laws for embedded trees
Cyril Banderier, Markus Kuba, and Michael Wallner, Analytic Combinatorics of Composition schemes and phase transitions with mixed Poisson distributions, arXiv:2103.03751 [math.PR], 2021.
P. Flajolet and R. Sedgewick, Analytic Combinatorics, 2009; see page 413.
FORMULA
G.f: x*c(x)*c(x^2*c(x)^2), c(x) the g.f. of A000108. - Paul Barry, Jun 02 2009
a(n+1) = Sum_{k, 0<=k<=[n/2]} A039599(n-k,k)*A000108(k). - Philippe Deléham, Apr 12 2007
a(n) ~ 2^(2*n-3/2)/(Gamma(3/4)*n^(5/4)) * (1 - Gamma(3/4)/ (n^(1/4)*sqrt(Pi/2)) + 9*Gamma(3/4)^2/(4*sqrt(2*n)*Pi)). - Vaclav Kotesovec, Sep 16 2013
a(n) = T(2*n-1,n)/n, where T(n,k)=T(n-1,k)-T(n-2,k)+T(n-1,k-1)+2*T(n-3,k-1)+T(n-5,k-1). - Vladimir Kruchinin, Sep 29 2014
MAPLE
a:= n-> coeff(series(RootOf(A=x*(1+A^2)^2/(1-A+A^2)
, A), x, n+1), x, n):
seq(a(n), n=0..30); # Alois P. Heinz, Sep 16 2013
MATHEMATICA
For[A = 1; n = 1, n <= 26, n++, A = x*(1+A^2)^2/(1-A+A^2) + O[x]^n]; CoefficientList[A, x] (* Jean-François Alcover, Jun 29 2011, updated Apr 23 2016 *)
PROG
(Maxima)
T(n, k):= if n<0 then 0 else if n=k then 1 else if n>0 and k=0 then 0 else T(n-1, k)-T(n-2, k)+T(n-1, k-1)+2*T(n-3, k-1)+T(n-5, k-1);
makelist(T(2*n-1, n)/n, n, 1, 7); /* Vladimir Kruchinin, Sep 29 2014 */
CROSSREFS
Sequence in context: A192905 A192207 A289593 * A148793 A180718 A318226
KEYWORD
nonn
AUTHOR
Ralf Stephan, Jan 21 2005
STATUS
approved