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A058521 B-trees of order 5 with n labeled leaves. 2

%I

%S 1,1,1,2,3,4,7,11,20,36,67,121,215,377,657,1154,2045,3666,6628,12063,

%T 22079,40642,75264,140191,262457,493297,929703,1754941,3314509,

%U 6258052,11803995,22232306,41801393,78453563,146987053,274957984

%N B-trees of order 5 with n labeled leaves.

%H <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a>

%F G.f. A(x) satisfies: A(x) = x + A(x^2+x^3+x^4+x^5). [_Geoffrey Critzer_, Mar 28 2013]

%p spec := [ B, {B=Union(Z, Subst(M, B)), M=Union(Prod(Z,Z),Prod(Z,Z,Z),Prod(Z$4),Prod(Z$5))} ]: [seq(combstruct[count](spec, size=n), n=1..40)];

%t nn=38;f[x_]:=Sum[a[n]x^n,{n,0,nn}];a[0]=0;sol=SolveAlways[0==Series[f[x]-x-f[x^2+x^3+x^4+x^5],{x,0,nn}],x];Table[a[n],{n,0,nn}]/.sol (* _Geoffrey Critzer_, Mar 28 2013 *)

%Y Cf. A014535, A037026.

%K nonn

%O 1,4

%A _N. J. A. Sloane_, Dec 21 2000

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Last modified October 23 22:42 EDT 2019. Contains 328378 sequences. (Running on oeis4.)