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A058520 Sequences of B-trees of order 3 with n labeled leaves. 0
1, 1, 2, 4, 8, 17, 35, 73, 152, 316, 659, 1376, 2875, 6004, 12535, 26173, 54654, 114134, 238348, 497743, 1039432, 2170634, 4532949, 9466295, 19768943, 41284768, 86218046, 180056039, 376025957, 785286555, 1639979712, 3424906290 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..31.

MAPLE

spec := [C, {B=Union(Z, Subst(M, B)), M=Union(Prod(Z, Z), Prod(Z, Z, Z)), C=Sequence(B)}]; [seq(combstruct[count](spec, size=n), n=0..40)];

CROSSREFS

Cf. A058518, A058519, A014535.

Sequence in context: A309908 A001357 A309462 * A127680 A136750 A274115

Adjacent sequences:  A058517 A058518 A058519 * A058521 A058522 A058523

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 21 2000

STATUS

approved

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Last modified October 21 14:13 EDT 2019. Contains 328301 sequences. (Running on oeis4.)