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 A052525 Number of unlabeled rooted trees with n leaves in which the degrees of the root and all internal nodes are >= 3. 2
 0, 0, 0, 1, 1, 2, 3, 6, 10, 20, 36, 71, 136, 270, 531, 1070, 2147, 4367, 8895, 18262, 37588, 77795, 161444, 336383, 702732, 1472582, 3093151, 6513402, 13744384, 29063588, 61570853, 130669978, 277767990, 591373581, 1260855164 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,6 COMMENTS Old name was "Non-planar unlabeled trees with neither unary nor binary nodes". I am leaving this alternative name here because it may help clarify the definitions of related sequences. - N. J. A. Sloane. LINKS Vaclav Kotesovec, Table of n, a(n) for n = 0..1000 INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 95 FORMULA a(n) ~ c * d^n / n^(3/2), where d = 2.2318799173898687960533559522113115638..., c = 0.3390616344584879699709248904124... . - Vaclav Kotesovec, May 04 2015 EXAMPLE For instance, with 7 leaves, the 6 choices are: . [ *,*,*,*,*,*,* ] . [ *,*,*,*,[ *,*,* ] ] . [ *,*,*,[ *,*,*,* ] ] . [ *,*,[ *,*,*,*,* ] ] . [ *,*,[ *,*,[ *,*,* ] ] ] . [ *,[ *,*,* ],[ *,*,* ] ] MAPLE spec := [ S, {B=Union(S, Z), S=Set(B, 3 <= card)}, unlabeled ]: seq(combstruct[ count ](spec, size=n), n=0..50); CROSSREFS Cf. A052524 and A052526. Sequence in context: A231331 A008927 A331488 * A006606 A120421 A005418 Adjacent sequences:  A052522 A052523 A052524 * A052526 A052527 A052528 KEYWORD easy,nonn AUTHOR encyclopedia(AT)pommard.inria.fr, Jan 25 2000 EXTENSIONS More terms from Paul Zimmermann, Oct 31 2002 STATUS approved

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Last modified June 25 08:27 EDT 2021. Contains 345453 sequences. (Running on oeis4.)