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A058518 Number of forests of B-trees of order 3 with n labeled leaves. 3
1, 1, 1, 2, 2, 4, 6, 9, 14, 21, 33, 54, 89, 142, 222, 350, 554, 883, 1406, 2225, 3511, 5539, 8768, 13977, 22417, 36143, 58483, 94818, 153716, 248699, 401054, 644485, 1032794, 1652377, 2642421, 4227547, 6769660, 10851491, 17410292, 27951747 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..39.

MAPLE

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

CROSSREFS

Cf. A014535.

Sequence in context: A274147 A226496 A047084 * A018139 A293640 A025049

Adjacent sequences:  A058515 A058516 A058517 * A058519 A058520 A058521

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 21 2000

STATUS

approved

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Last modified June 18 18:52 EDT 2019. Contains 324215 sequences. (Running on oeis4.)