A058520 - OEIS

A058520

Sequences of B-trees of order 3 with n labeled leaves.

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

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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